To me it's more a curiosity than anything else. I don't see it as a paradigm shift and I don't see it as something that worthy of a whole lot of attention.
R..
I don't see it as a very big deal either actually. When people ask me why I dive in a different way using such a strange setup, my answer is "how is it different from what you have on your back? There's a tank, 2 regs and a spg, I'd let you carry your tank in your arms if you wanted to, as long as it stays with you I'm fine". That is for easy 1 tank dives (which all of my dives are atm).
Now with 2 tanks, that's where you have to learn procedures that relate to your gear setup. Valve shutdown, knowing which one to close, how to do air-share etc etc.
Some people say this should be in a sidemount essentials course, I believe it would very well find place in the intro to tec course. For the obvious reason that when someone in BM comes to intro to tec, he's expected to having done only single tank dives, why should that be different for someone coming from SM?
Now when we add stages, those are mounted slightly differently in SM than in BM, someone diving with stages at 90° in SM will be laughed at. Procedures may or may not be the same, I don't know that, I assume they are because I can't see why they should be different.
For that whole gas loss dilemma, I really don't get it. Suppose you would (which most of us seem to say you can't, but let's not diverge on the fact that it could be possible) be able to indeed lose half your gas. Doesn't that simply become part of gas planning? Rather than "oh my, now I won't have enough to get my ass out of here", it seems very wrong to me to go to a point where you could indeed be able to not make it out with enough gas. When that happens in BM, it's called "poor planning", why should it be called "****ty configuration" when it's sidemount? Then it won't get you as far as BM in a cave (except the guy in BM won't be able to pass the first restriction), but does that mean it's no good?
To be honest, I've bought the stealth because of the tons of pictures you can see of Santiago Pintado, Steve Martin etc, and knowing that it's safer for solo diving (which will eventually happen later on), because whatever the **** you do, you can't lose all your gas, and those dives would be dives that always allow for an ascent in less than 50bar on a single tank. I had considered a bpw setup, almost bought one when I saw SM, so here I am now. Since those guys are able to dive to 80+ without any problem in SM it never even crossed my mind that I'd be told off by instructors because "SM is no good when you carry a stage", I did know however that some instructors were very close-minded about sidemount, but those were supposed to be mainly "noobs" or hardcore DIR divers. Since to me DIR doesn't me technical and technical doesn't mean DIR, I didn't expect it to be impossible to find an instructor for "basic" tec courses that would let me dive "the way I want".
Anyway, I think in the end I'll just wait until I get a chance to see a SM instructor to do those courses, and keep training on my own in the meantime. Maybe next year, maybe even later...