I love the silvers, but I don't breed them anymore. Breeding silver to silver is a bad idea. That can be a lethal combination with low hatch rates and a much higher rate of albinos with health issues.
Jumbos are pretty much jumbos. The standard browns will usually get a bit bigger (not enough to matter), but the big advantage to them is that they're feather sexable, which the whites aren't.
If you're raising them for meat, it makes more sense to be able to tell their gender at 3-4 weeks...