Interesting...well I tried it both ways. But, when I did it in the recommended sequence (stabilize first; speed up 2nd) it required that I restabilize, as it is now a shorter length. So, I'm not really sure if I've gained anything by doing it that way. Difficult to make an objective evaluation.
Well, Len, if I were to speed up shaky footage I'd have really REALLY shaky footage to the de-shake in Mercalli. My guess is that Merc would over-compensate and make a motzah puddin' of the results.
Stab first then slow down. I've been using this with TWIXTOR - I'm happy!
I'm NOT happy with the Wall O' Silence from SCS regarding our beloved Vegas Pro though?
I would stabilize, then render that to an intermediate file. Then speed up the rendered intermediate.
An alternative would be to stabilize first, and then render to an image sequence. Use the image sequence import and set the playback frame you desire for the speed you want.