Don't get me wrong, I've tried it, and failed like many others before me. I'd tried the uberman method for about 2 weeks before falling, and I didn't feel very productive during that time at all (although there were times that I felt more awake than I ever have done, and time seemed to merge, days didn't exist... it's a weird feeling)
I've now adapted the old version of polyphasic sleep, take a nap in the afternoon and sleep for about 6 hours on a night and it seems to be doing me well :)
But! I am tempted to give the uberman method another try, and I will write about it if anyone would be interested?