I know this is a C&V forum, but since you have a Centurion 10 spd, I don't see why you should get another older bike for your second, unless you already know you want to start collecting C&V bikes. In your case, I'd look for a newer, sportier bike. You can probably find a lightly used carbon or aluminum for sportier days in the saddle for not much more than your two candidates.

Btw, only the really old or very entry level new aluminum frames are going to beat you up. Any new Cannondale, Giant, etc are going to ride very nicely. I have a 2001 Klein Quantum Race, a 2003 Fondriest Carb Level (al w/ carbon seat stays) and a Colnago Mix (al w/ carb ss) and they are all very smooth. The Fondriest especially is as smooth as my carbons.

I say this, as I'm paring down my road race machines and wanting to expand my range of bikes- don't have a rando, and SS/fixie.