well, most say that any hub is compatible with any cog, unless you're racing different events on the track and changing JIS on ISO all the time or vice versa; I never tried the Miche cog thing because my hub came with a 15 and I was running a different ratio. Re: the micro difference, I just got a Phil cog because I was feeling spendy, but you're hardly limited either, with EAI, Phil, Miche and Campy all working per spec.