No need to look elsewhere! Seriously, I might ride some Specialized, Treks, Giants, etc... just to get an idea about what feels best. The R900 is a great bike and the Campy shifters are super. 50 sounds a little small, but I'm 6'1" and ride a 58, my wife is 5'6" and rides about a 50. I would at least try a 52.
You usually know fairly quick if you like the bike or not. Last years R900's had a horrible seat, but that is easy enough to swap. I would ride as long as the shop will let you.
John
__________________
Time to Ride...