Almost all my GUE instructors were using Halcyon regs in class. Not a very meaningful sample. I agree that if there is a GUE group local to the diver then see what regs they are using. If the OP lives in Kona, there's a whole lot of nice diving to do there, and I'm a little confused by the interest in freezing waters. Hey
@nicpub , did you take Fundies with Mer?
I'm in the Deep6 camp because being able to service my own regs has saved me more and more money as I started accumulating regs for doubles, then stage and deco bottles, etc. Having all my regs the same may not be realistic for everyone, but I like it. Deep6 are good, all-around regs.
I'm not planning to dive in Antarctica, but if I were going to shell out $20k or whatever for such a trip, I would probably not balk at the cost of acquiring a few more regs, a heated undersuit, heated gloves, and all that. As far as I know, the Deep6 regs are fine for normal cold-water diving. Antarctica or ice diving?--I really have no idea what that entails.