You are simply welcome to try that and we would definitely like to see your results. I looked around and didn't see any binaries for the development snapshots for windows to test. That means you have to compile postgres in order to test 9.2 at this point in time. Testing and feedback of index only scan feature would be very much appreciated.
Generally speaking, postgresql source tree is very high quality -- stuff should mostly work. The biggest annoyance is that you get lots of catalog version bumps when pulling new versions of the sources forcing a dump/reload. merlin
