Would agree that the top tube length may be the more critical measurement. And if both of these sizes are on 700 wheels I'll bet you'll find that there is not much difference in the top tube length. If crotch clearance is OK on both sizes then the biggest difference will be in the saddle to handlebar drop and stem length. I would avoid having to go to a short stem, less than 100mm, in order to get comfortable with the length of the larger frame size. If you take the smaller size the problem will likely be getting the handlebar high enough. At least these are the variables I would be concerned with, YMMV.

Al