We are getting a bit confused here between 'full stall' and 'deep stall' I think, and in the case of 447 it was being held in a (amazingly stable) full stall (not a 'deep stall') by THS setting and elevator, although I don't think any research has been done (for obvious reasons) on the longitudinal stability of the 330 in those conditions and it may be that there is an unexpected aerodynamic strong nose-up moment (Edit: I have just seen Lyo's frightening post regarding loss of elevator function, so yes, it looks as if could be described as a 'deep stall'). Regarding min recovery height, it is simply enough to do the sums, and I chucked my hat in the ring way back to say that I thought 20k would be the last point for recovery without hitting the water. This simply based on a descent rate of 10k a minute (2 minutes to impact) and a required pitch change of something like 40-50 degrees nose down, taking a few seconds (which would drastically increase the 10k down) reducing the remaining time, and then add the altitude required to transition from that descent to level flight without pulling the wings off or entering a manoeuvre stall. All subjective, of course - I have no desire to check my estimate.
DC-ATE - are you saying you were in a 'deep stall' (whatever you think that is) with 10kfpm down at 10k in IMC? Sounds like some really smart flying there to achieve that. I think I would have taken control a little earlier and called for a psychologist to meet the a/c on arrival.