I was able to get one used (not in hand yet) but I was looking up this reg and it seems it's cold water capable and I can even get parts to turn it DIN as well as get it sealed for ice diving (which I hope to do next year). Is it also good enough to be used for tech diving? I'm still pretty new but would be interested to head that route. If not, I'd just keep it as a rec reg.
Yes, the V16 Proton Metal is an excellent choice for cold water diving. In its original state, it is very unlikely to encounter freezing issues (down to 50 degrees Fahrenheit) if you follow proper cold water diving protocols.
I use V/MR16 first stages for ice diving, and none of my three are sealed against the ambient water. However, with that said, using the Mares CWD kit would offer even more protection against icing conditions. I recommend using the newer dry sealed system (CWD Dry Kit)
Mares - just add water, as it is easier to maintain and is likely less susceptible to damage.
All of my Mares regs that are used for technical diving are fitted with DIN 300bar fittings. The same link as above illustrates a DIN fitting that is listed for MR42 and MR22 first stages. It is also compatible for use with the MR/V16 first stage. The kits instructions identify the proper placement for the included O-rings.
As far as tech diving use goes...I've been using the V16 and MR12 first stages for all of my deep/cave/wreck diving for the past ten or so years. The Proton Metal is my hands-down favorite Mares second stage.
That said, here are a couple of pictures of me following an ice dive. On this particular dive, I was using a Mares V42 Proton Metal unit. The surface temp was in the 20's, which explains why my gear begin icing over within minutes of exiting the water. The other picture clearly displays a bail-out bottle. When I am ice diving, I typically wear doubles. On this particular dive, the exit was going to be a bit tricky, so I didn't want the extra weight while climbing up a wooden ladder.
Greg
