So, since you haven't bought wheels yet...

I would recommend demoing some wheels if you possibly can, especially whatever you think you are going to buy. There's more than meets the eye - stiffness and how they handle in wind are hard to describe, if you can try them it would be good.

Also, make sure they fit in your frame, I have a Scott Plasma TT bike that I can't put my Zipp 303 front wheel on, the frame is too narrow.