Polyphasic, no - but biphasic doesn't seem to have any negative affect on recovery. I'm currently getting a little under 6 hours (roughly a 1.5/4.5 hour split), and it seems to result in better quality sleep than I was getting before.
A few observations :
The weights/reps haven't decreased for any exercise since the switch (a couple of exercises use the same weight as before, but other aspects have been adjusted).
My weight is stable, although I haven't been actively trying to change it. Same goes for bodyfat.
I feel more refreshed after the 4.5 hour core sleep than after 7-8 hours when I was monophasic.
During the first week of the transition from monophasic to biphasic, I knew I was going to be tired and kept away from the weights (no easy task, but worth doing). The first couple of sessions afterward were the same as you'd expect after a week's break for any other reason.