RE: Is a 50caliber Muzzleloader better then a 45caliber?
The 50 wins due to sheer flexibility and popularity. You can just do so much more with it. However, if you're going to specialize in longer-range shooting and focus on .357 or .40cal bullets pushed as fast as you can (and they indeed still show accuracy at the highest velocities) then a 45 is just fine or better ballistically.
I'd add a .45 to my lineup if I got to shoot enough lately to have time to work up multiple guns. Right now working up my long range and short range 50s is all I have time for at the range despite that range being in my backyard. Plus, I am not aware of a production .45 right now that I'd pay for.
The 250 SW is the worst of the lineup. Ballistically inferior to both the 200 and 300, and performance on game is fine but not as controlled as either of its brothers. I think the longer-for-caliber design of both the 200 and 300 help hold them together in the non-bonded designs than the 250.
I'll stick with the 200 unless this FTX thing works out, ballistically they look good but I have to shoot a few deer to make up my mind on performance. I know Grouse doesn't like them but I have to shoot a few to make up my own mind. I've shot very few bullets I didn't find acceptable.