I am thinking of converting my Optima Lynxx to a 700c highwheeler. I have checked, and have frame clearance that will easily allow for this.

Some questions I don't have an aswer to:
1) What will this do to the handling of the bike? (currently 20" front, 26" rear)
2) Will it be possible to get rear brakes that will work? The Avid's I have on right now are too low to make contact with the 700C rim in the right place.
3) Is there any reason I should not do this?

I am on a quest for speed, but still want to be able to ride longer distances.... Plus 700C wheels makes the bike interchangeable with the weggie I have to race with.