Quote from Lazerdog:
"As they were descending in the the stall through 10,000 feet, the THS was trimmed up automatically."
All of us are occasionally running into problems of ambiguity, due to the inherent limitations of written language. That's why the FBW design engineers have to avoid it. I'm sure you don't mean to imply that the autotrim was still changing the THS trim position as AF447 was passing 10,000ft?
The BEA Update is not entirely free of ambiguity, but it states:
"At 2h 10 min 51, the stall warning was triggered again. [...] The... [THS] passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight."
Read it yourself and draw your own conclusions, but my inference is that the 13degNU was reached at around the apogee (38,000ft) or soon after.
Lazerdog, quote:
"Would full forward side-stick have caused immediate stall recovery, or would the PF have to wait until the THS auto-trim caught up with nose-down trim?"
Short answer is: don't know. But I think we can expect that the AoA would have started to reduce immediately. Unless the THS motor stalled, which would be unlikely at such a low airspeed (low loading), the THS would have started moving immediately. I don't know its maximum rate. What do you mean by "anhedral trim scheme"? What does "kinesthetic" mean in this context?
The BEA Update indicates that the aircraft passed 10,000ft at or after 02:13:32. The rate of descent seems to have been in excess of 10,000ft/min. The process of stall recovery would have increased the ROD initially...