LUBOLD8431:
The R2 is just a basic unbalanced piston. It would be fine for an Instructor or LDS for students in the pool and a nice rental reg for open water dives. Its not a high performance reg, just a simple design.
The R2 is exactly what Lubold has stated. It is basically the same as the ScubaPro MK2 first stage, and on the ANSTI simulator has almost identical scores. Dive buddies and I use them as deco regs for EAN50 and oxygen, as the depths are rather shallow. You can switch the regs on bottles underwater if need be (only when a failure dictates), and they are extremely simple to service.
That being said, they do have their limits as all nonbalanced first stages do. I believe that for everyday sport diving, the MR12 is a far better choice. The MR12 first stage has only one dynamic O-ring and is rock solid. It offers very good gas flow at approximately 4,000 liters per minute. When one considers that the vast majority of second stages can only flow around 2,200-2,800 liters per minute then its capacity looks even better. In layman's terms, two divers breathing at an aggressive rate can still get sufficient gas at 165 feet. I mentioned some time ago a little test that I rigged up. I was at around 120' and started purging my backup reg, while breathing very aggressively on my primary. I still didn't feel like the reg was failing to meet my demands. This is a rather severe test and has led me to trust the MR12.
Diving below 150fsw on air is NOT a wise choice, so when helium based mixes enter the picture then the work of breathing becomes even easier.
Just for interest, I use MR12's on my doubles. I use the Akros second stages for their cold water dependability. On my single tank rig I use a V16 first stage with a Proton primary. The V16 has better hose routing for singles, but the MR12 works fine for my hose routing on the doubles.
I am not advocating that Mares regs are the ULTIMATE choice. They are my choice because I am able to service them and parts availability is not an issue with me. I have a stock of parts that will easily cover me for more than a decade. They are generally very reliable, and offer excellent performance for such a simple, robust design. If you want or have a need for greater gas flow, or have the desire to have a user adjustable second stage then I would consider the Apeks brand. I am very impressed with their design features and detailing. There are many fine regs on the market. I honestly wouldn't feel shortchanged to use any of the higher end models from any of the major manufacturers. I personally prefer diaphragm regs, but many of my dives are made in cold water. If I only dove in warm water, then a high flow balanced piston first stage might get the nod. Till then, the Mares regs will continue to meet my diving duties. I've never had one fail me yet....
The key is to find a reg that can be serviced by an individual that you know and can trust. A reg should never be serviced by a "parts changer". Anyone can be taught to simply swap out parts. A true technician fully understands the mechnical principles of the reg that they are servicing. They take no shortcuts and service the reg in such a manner that they would have no qualms about letting one of their loved ones use it. If you can't trust a reg technician then you would be better off with a brand that can be serviced by a competent individual.
Safe diving!
Greg
