the only likeness you can really apply here is that nitrogen and oxygen partial pressures affect as all differently similar to alchol, there for we all dive conservativly, intresting enough theough in one of the UK mags last month or the month before a BSAC guy was all for reverse profiling, can see his point about building up to deeper depths etc but poses the question why its so frowned upon?
Also was going to ask andy as you may know this.
down this way BSAC clubs along with SAC have a monthly mebership cost, is that something that happens nationally, I only ask as the club I belong to is free, but we pay for dives (fee varies depending on how far out the dive is)?
Also with reference to ascent rates most of us will be diving on computers which are very conservative (way less than 18m per min advised) even with this in mind I have seen more rapid ascents than i care to remember.
Incidently I have to say one of the worst dive organisations I have experienced is SSI, they were that bad they encouraged intercation with marine life and were even encouraging sumersault entries off the dive deck of a live aboard!