Is there an actual advantage to BBP vs SBP?

I will pile on to the "best" answer of, "Your wheel and tire choices will be a zillion times better. I too did a front disc brake conversion that gave me the SBP vs BBP choice. You can either EASILY buy two new BBP axles that are ready to install, or you can have your current axles re-drilled for BBP. In my humble opinion, it REALLY boils down to that.

I thought the center register was a different size between the two?