Nice presentation of the issue, Bobby. Divesherpa, I think the idea here is that many of us try to standardize our equipment configuration and use the same configuration whether diving in the keys or up in cave country. Check out the GUE website for a good discussion of this issue.
For the record, I'm neither a caver or a DIR diver, though I think that both of these groups have some very good ideas regarding diver safety.
Obviously, there are differences in opinion on this, just as there are over the AirII, which I don't like. I also don't like teaching students to kneel on the bottom, though, or to give lip service to the buddy system while allowing "same day, same ocean" buddy teams. All of these practices seem to be pretty common in the Keys, and while I love diving there, I'm always a bit concerned by some of the cavalier attitudes that I see down there.
But to be fair, I've also dived with many very good divers there too. I just don't see the harm in teaching students a more safety-oriented diving style.