I just wanted to agree with St. Pauli. I wouldn't skip K without visiting both the Kindergarten and 1st grade class in question and taking into account both the child's personality and the teachers. I have a son who just finished 1st grade yestday (hooray!).

Kindergarten actually went fairly well for DS. Things moved quickly day to day, lots of hands on open ended stuff, flexible teacher. 1st has been quite horrible - inflexible, very dry, much sitting still required, and not even close to what we would have liked for this year. It would have served us well to skip 1st (although, for my DS, he is quite happy socially with his peer group, so skipping is a tough call). He'd need more than 1 skip to actually be learning.