[John Rogers]

I would think the use of the bike would decide which type of frame to buy. If you were to do a lot of moutain road racing where you are sitting down and working hard with the bars and pedals, then I would want the larger frame and shorter seat post to reduce flex. On the other hand, for criteriums and short circuit races the small frame would probably be better since you will be sprinting a lot while out of the seat. For just plain fun riding, it would make no difference I suspect.