I got a pair of Napoleon mirrors for my '05 City X for the same reason. They vibrate far less and are a larger rectangle. I got mine from http://www.holeshot.com/ , where I got my exhaust can for my V-Strom. $46.95 per set (long stem).
Keep the mirrors; that's not the problem. Trade the bike for a Ridley. Same H-D Evo, just tweaked a little differently. I've heard they're real smoooth throughout the rev range. Might cost you a little extra, though. Used Ridleys are tough to come by and the new ones are commanding top dollar.
I think what the guy said about bar end mirrors is interesting. I don't know if they vibrate more or less, but they are they only was to go if you are actually interested in seeing behind you. At first, I worried about them getting broken if I ever dropped my VFR, but they would actually be about the cheapest thing on the whole bike to replace.
I recently put CRG Hindsight LS mirrors on my '04 Lightning and am absolutely satisfied with them. Vibration seems to affect them less and the optics are light-years ahead of OEM. I originally bought these purely to get rid of the bug-antenna OEM mirrors for aesthetic reasons, but I was pleasantly surprised by the gains in rearward visibility. They're not cheap, but you get what you pay for. Highly recommended!