Here you go.
http://www.magnumresearch.com/BFR-Factoids.asp
Toward the bottom of the page it lists the different calibers with some bullet/velocity data. To me the 30/30 doesn't look too impressive.
I bought the 460 last year. It's a lot of fun. Shooting most of these calibers almost requires reloading. Otherwise you won't be doing a lot of shooting.