FWIW, nitrox use is pretty common among recreational divers as well, and mixed gas diving is all but a must for tech diving. 32 and 36 percent O2 are most common and up to 40 is ok without taking extra equipment precautions.
I wonder if, or why, SCBA gear would use different tank valves than SCUBA gear such that any dive shop couldn't fill one.
Good point. I don't actually know for a fact that they are different. It may actually be the case that a dive shop would have the capability to fill an SCBA bottle. Now, whether or not they'd be willing to do it is a different question.
I wonder if, or why, SCBA gear would use different tank valves than SCUBA gear such that any dive shop couldn't fill one.