I'm going back tomorrow to do some test riding. They have a 48 as well to try, although not in the cannondale I was considering. I trust this shop and the store owner is assisting me herself. They have been in business for years and are well thought of by the local bike community. She mentioned what you said about the stem as well, and thought we should see how the 48 fits just to compare. I don't know why, but I feel scrunched up on the 48. Maybe I am just not used to how a road bike should feel? Or perhaps the geometry is slightly different?