I'll just say right off the bat that I'm biased against the 41 Mag. If it's your thing, and you reload, it'll do the job. I also note that a lot of folks report great accuracy with 41 Mag handguns. Hmm. But the 45 LC can do it all, especially out of a Blackhawk. There are loads you can run out of a 45LC Ruger that would raise eyebrows even among 44 Mag shooters, and the Long Colt will do it at lower pressures, to boot.
Now, I've heard about loose chambers in Rugers, my 44 Mag SBH has 'em, but you can always have a gunsmith open up throats that are too tight.
EDIT: To answer your other questions, yes a 10" barrel will show substantial velocity increases over the 4.6". My SBH has the 7.5" barrel. It's fine, but the shorty would make a better-balanced gun.