If the MacPro is cheap enough it should be just fine.
I've been doing this with a Mac Mini since '09.
My latest mini is a '12 i5 with a Samsung 840 Pro 256. 3x WD 2TB USB3, 2x 6TB WD Thunderbolt Duo, 1x 2TB WD Firewire 800.
I run a personal website, wikipage, iTunes server, CrashPlan Server, TimeMachine Server, caching server, etc etc etc.
This serves 6 aTV's, 3 iPads, 2 laptops, 3 iMacs and 2 iPhones.