microburst8265,
The decrease in AOA crit is VERY significant. If the pitch attitude, which is just below stall in the clean configuration, is MAINTAINED, the decrease in AoA crit as compared to the existing pitch attitude is the cause of the stall.
I have tried the very manoeuvre described here, very difficult to accomplish unless you have sufficient elevator authority to overcome the pitch down produced by lowering the flaps. When I was younger and much more stupid than I am now, I investigated stall speeds when inverted with Flaps retracted and Flaps Down (or is it Flaps Negative Down when you're inverted), oddly enough, it didn't seem to make any difference. Not too inclined at my age to investigate it further.
Regards,
Old Smokey