This is a great question and one you should really be asking yourself when wanting to get into this sort of diving.
Below I have tried to give as unbiased approach to the pros and cons of deciding which way you should go. Having spent years diving on open circuit and the last 14 years on closed circuit I have a pretty good idea of both sides of the discussion - but at the end of the day you and only you will make the decision. Hopefully this will open your mind and answer questions you may have regarding breathers.
RECREATIONAL OR TECHNICAL???
A lot of people ask themselves the wrong questions when inquiring about getting into rebreathers. The first obstacle is
"I don't do enough diving to justify the expense!" - Sound familiar???
I come across this all the time. This always reminds me of the average Kiwi who owns a boat. Average expenditure people have on boats is around $30-60K.
What I want to know is on average how long does that boat spend in the garage each year? Most of the time it is tucked away for 10 or more months of the year. Does that "Justify" the expenditure? HELL NO but we love just getting into our boat and heading out with no worries don't we!!!!
I am married with 2 kids so I don't get out as much as I want to so when I do get out it is a special event that I want to maximise my time on. On an average recreational days diving that I do ( NO decompression) I spend about 100minutes per dive on a two dive day. That's 200 minutes for a days charter. Most people will do about 45 - 50 minutes in the water each dive on open circuit. That's 50% more value I just got out of my trip! What's more I didn't need two tanks and two fills for that either!!!! So you should be asking yourself -
I AM NOT A TECH DIVER - ARE THERE REBREATHERS FOR RECREATIONAL DIVERS?
We get this often....
"I am not into technical diving I am just a recreational diver. Rebreather's are for technical divers aren't they?"
The biggest difference between recreational
rebreather diving and technical CCR diving, at the entry level, relates to how divers respond to life-support related problems. This is central to the philosophies
and demands of using rebreathers in the recreational versus technical environments.
In recreational or technical open-circuit diving, the primary response to a life support
failure (out of air, etc.) is to switch to another life support system such as an alternate
air source (recreational diving) or secondary regulator (tec diving). Beyond minor issues (such as sand in a second stage), no attempt is made, during the dive, to return to the faulty regulator.
Recreational rebreather diving follows the same approach. The default response to a serious warning indicator is for the diver to switch to open-circuit bailout and end the dive. The types of issues related to life support that a recreational rebreather diver would attempt to resolve to stay on the rebreather are small in number and uncomplicated. This is consistent with open-circuit
diving and familiar to recreational divers. Retaining the philosophy of switching to another life support system significantly simplifies what divers need to know to respond appropriately to a Type R rebreather emergency.
Technical CCR diving differs from open-circuit tec diving and both open and closed-circuit recreational diving in that the diver may, depending upon the circumstances, abort the dive while continuing to use a malfunctioning CCR. Following a serious warning,
the diver bails out to open-circuit, but then diagnoses the fault. Depending upon the nature of the problem and the circumstances, a tec diver may elect to return to the CCR and offset the problem using manual controls and other emergency procedures. Although a tec diver should have adequate open-circuit bailout gas to safely abort the dive, returning to the CCR substantially reduces decompression time and conserves gas, retaining resources for handling subsequent problems that could occur.
Learning to diagnose and respond to CCR problems by returning to the unit adds substantially
to the training requirements compared to recreational rebreather use. It also adds to the complexity of operating the CCR. Type R rebreathers typically eliminate redundant gauges and manual controls required on Type T (technical) CCRs. Type R rebreathers
may also be SCRs (semiclosed-circuit rebreathers), which are not commonly used in tec diving. These differences in hardware and psychology are why, before making
dives that involve physical overhead (caves, wrecks) or virtual overhead (decompression
stops), the technical CCR diver needs adequate experience using the hardware and applying this mindset within no stop limits or very limited decompression diving.
The market is now mature enough that most tech divers will think hard about rebreathers and what they can do to their diving that will benefit them.
In order for you to enjoy your diving on a rebreather and reap the many benefits of using these fantastic tools you will need to get comfortable and dive on your breather.
ADVANTAGES OPEN CIRCUIT
Firstly it is something that you already possess the most experience in. You are well tuned to the operation and procedures in open circuit. It is predictable and easy to use. AIR in tank - air to breath NO AIR in tank - NO air to breath!! That simple. Cost wise you might have some of the gear already so you can simply add to your kit to get you to the desired configuration. You can go out and do relatively advanced dives after a long period of inactivity ( although not recommended you still have the experience to be able to get out there and go and do it) There are more open circuit people than rebreather divers. Underwater problems are more definitive and immediate and you don't have to use too much brain power to solve problems - gas leaking, isolate leaking reg/valve. Reg has problem, switch to the other, etc etc. This leaves you to be able to dive a lot sooner to deeper areas than breathers. Predive checks are more simpler and less time consuming.
ADVANTAGES OF REBREATHERS OVER OPEN CIRCUIT
I will talk about the inspiration rebreather for the advantages. First of all probably one of the biggest ones is that you are the closest to nature than you ever thought possible! With OC diving you are loud as hell, scaring fish in all directions. On the breather you really are in the silent world, so if you are into photography or videography you will be amazed how a part of the underwater world you really become and all teh fish just go about their business for you to capture on film.
From a gas usage point of view hands down kicks ass!!! On the CCR you are using one litre (on average) of oxygen a minute regardless of depth. Your Diluent you would use about 20-30 bar out of a 3 litre tank per dive. SO that means that you have roughly 500 minutes of dive time one one tank of Oxygen. Comparability tests with OC is roughly 200 times more productive.
Nitrogen management - On a CCR you are basically breathing the optimum gas mix CONSTANTLY on a dive. For example if you are at 30meters you would be breathing a EAN32 mix. You ascend to 20meters you are automatically breathing a EAN43 mix, 16 meters EAN50, 12 meters EAN60 so basically you are offgassing using the best mix all the time. This can only be done on OC by carrying about 8 different gasses with you!!! Here you can spend huge amounts of time at 20-30m with ridiculous NDL times!!!!
TRIMIX applications - A lot of people are nowadays wanting to spread their wings and explore deeper sites, wrecks and need helium to be able to get them there (and back). But with Helium costing 12-15c per litre this could prove expensive if you want to pursue this sport (that's on average about $250 for a 75m dive and about $320 for 100m dive in GAS ALONE!! Remembering that a breather only uses the diluent to equalize the breathing counterlungs and after that no more gas is used. I have completed about 15 dives to 85 meters on a single 10litre tank of about 25-35 minute bottom times and the tank is STILL at about 150 bar!!!!! So if you are wanting to get into trimix then you will pay for your breather in no time if you are worried about dollars!!!
Flexibility - A standard inspiration can go out and do 100m dive by simply adding side slung tanks. If you don't do a trimix dive you simply don't take the sideslung tank!! Now if you just filled your set of twins with trimix ($250 bucks later) if the dive was called off you would be stuck with that gas in your tank. So you could not do anything else with it.
You need to really ask yourself how a breather is going to help your diving. If it is - get one. Do your homework on what breather to get, and above all make sure you get trained by the best person money can buy. Your life depends on it!!!