My solution to most of the problem is to "ease" into the schedule. Keep a core sleep period of like 4-5 hrs at night but continue to take your naps. As you acclimatize, try shrinking/eliminating the core sleep gradually. That way you dont feel like you're getting hit by a train like you do if you try and jump right into it.
As far as code quality, I find mine is actually much better.. The period just after each nap I feel really refreshed and can concentrate. Theres actually research out there that proves this is true. Again, I think its all about avoiding a rough acclimation period though..
hmmm.. I found research in this area very lacking. The only scientific study seemed to be from sleep researcher Claudio Stampi and his essentially said "If you absolutely can't keep regular sleeping schedules (like in long sailing races) then polyphasic sleep is a better alternative".
If you have pointers to papers I'd appreciate links sent to the email-id in my profile. I might try this again someday.
I'll shoot you an email if I find more.. My co-founder knows more about this stuff than me I'll ask him.
While you do suddenly seem to get a lot of time it makes any kind of socializing hard since you have to sleep every 3-4 hours. Even after a couple of months if I missed one sleep session I would hit a massive wall and all coding would come to a stop.
Lack of time can sometimes be a good thing. It forces you into creative solutions. The funny thing is, although I produced more lines of code during the polyphasic experiment I think the quality suffered (not much but when I look over those pieces it always seems I could have structured it better). I don't know what to attribute that to since I didn't feel any different while coding in or out of the polyphasic state after the ramp up period.