I'll offer my 2 cents, which interestingly echoes most closely a non-instructor.
First, my shop would prefer we use gear they sell. Not one particular model or brand, but something in their range. I mostly do that, but because they sell quality and I get a pretty steep discount on any gear I've bought over the years. Other instructors don't, and there's a little behind the scenes grumbling by shop management, but nobody is "fired" over it. More like peer pressure from respected peers.
The shop doesn't mandate gear configuration either. Some use doubles and long hose around the neck, some the same reg setup the students do. So very much a "no pressure" environment.
All that said, I dive a backplate/wing with a standard octopus setup when teaching. I don't think the students realize (until I point it out) that my BCD is different from theirs. (They don't all dive the same make and model of BCD out of the rental fleet, either, so it's not like they only know one BCD.) The power inflator works the same way as theirs as does the deflator . It's got a baggy bit on it that inflates and some strappy things that attach to me and my tank, the same as theirs.
I don't use an Air2 because I want to look like the students when demonstrating skills and also because it's less than ideal when teaching lift bag use in an Advanced class. (I always do S&R as one of the dives in Advanced.) At work, I tend to use a lift bag on occasion as well so it's just easier all the way around. Lastly, I'm just not a fan of the system, but your mileage may vary on that.
I understand and appreciate the notion that you may be matched up with an insta-buddy who has very different gear. However, you can't show every possible weird configuration said insta-buddy might show up in. To get around this, I tell students there are a few things they MUST go over with a new buddy. One of those things is how that person will donate in an out-of-air situation. Hand the secondary off or the primary? Or just "do the dab" and let the victim grab it themselves? (I also emphasize discussing where the weight is located on the buddy, so in an emergency the know how to drop their buddy's weights.)
So if the OP wants my advice, I'd say get a standard octopus, but stick with the back inflate BCD.