Good report Mark. The question of difficulty at 6m is an interesting one, I have doen a few dives at Wraysbury and off the 6m shelf at Stoney and you are so right in how much a minor movement has a dramatic affect on bouyancy. I suppose its something we dont practice that often, given that we are diving 30/40/50m wrecks in a very square profile. It may be that a good pre DIRF practice would be to get that 6m stuff sorted to a high level.
I find it very interesting that a hugely experienced diver such as yourself struggled on the course and received a provisional rather than a pass, perhaps its an analogy to an experienced driver re-taking their car test, I suspect we'd all fail that one!
After years of DIR bating I think your honesty in the report very brave or stupid.
Hope it goes well for you on the re-assesment.
Its certainly whetted my apetite to seriously think about doing it (the course) apart from having to get rid of half my kit, or replacing some of it, of course!
Matt