I'm still with RAT here. I'm not particularly happy if after having my rapid decompression I find myself tootling over a hold for LHR on QNH when every other aircraft is on a FL. It's madness. I still think a descent to the level below FL100 when above the transition should be taught. Either that or as others have said - sort of the level so it's above 10,000! If you have the ability on comms to get QNH then you have the ability to tell them you'll stop at FL90.
Surely this all comes down to your situational awareness?