I have researched internet a little bit a couple of years ago on the topic of polyphasic sleep and my conclusion was that it was not worth a try. Of course people who invented the idea and hardcore supporters would not report any health problem. However a few people in communities I personally trusted did say, that while the state is sustainable and productivity for *mechanical work* is high, the creative component becomes hugely suppressed. You are fine, you feel quite comfortable but the state you are in is reminiscent of auto-pilot, you do things best that does not require you to be creative.
In addition, I think that it's hard to dispute that this way you are entering an altered state of mind and I personally averse to anything mind altering artificially. There are more that I would like things that would do this naturally, so anything that does that on purpose - I'm against it.
And of course you are right that everything is not for everyone. Any "teaching" any technique would not work for at least some people.
