I'm with Shortstripper. Interestingly, I've also had the opportunity to explore assymetric stalling in an extra.
I would tend to slip before extending flap - it's the irreversible nature of flap extension that puts it to the bottom of the toolbox for me.
The argument for speeding up - that is - making the wing as inefficient as possible (without irreversibly changing its shape), also makes sense to me. I would advise against thinking in terms of "rate of descent", rather it's the angle. The further away from best glide speed one is, the shorter (not necessarily sooner) the distance covered until touchdown.
On slipping - I agree with Shortstripper's description of behaviour approaching the stall in a slip. Yes, there is roll, but it's the right way, and gives an opportunity for correction, as long as the ball is low, not high.
I will ask one question though - 1g stalling speed in a slip versus balanced flight for a given config etc... Which is higher?