To the best of my knowledge, the only difference is the physical dimensions, and just about the only cards in CFII spec are Microdrives. So unless you buy a Microdrive, you'll be buying a CF1 card. As far as Microdrives are concerned, I plan on avoiding them, even if they are a little cheaper. I don't like the idea of extra moving parts, and the price gap is shrinking. But there are a few Microdrive apologists out there, so they may say differently...