I have C1s in a 14.5' x 22.5' x 8.5' room, and they sound great, other than bass. Bass is fine, but not great, and I agree with Mission that C4s are the next step, C2s are not worth the price.
Your room should be fine for C1 if you can keep them away from the walls behind and to the side of them. If not, they won't reach their potential.
Mission, what size is your room with the C4s?