I am a happy 45cal owner and I don't regret my choice BUT my next muzzleloader will be a 50. You have more bullet selection, accesories are easier to find, it is legal in more states, and with the Omegas the 50 balances better than the 45 due to the slightly lesser barrel weight (both barrels are the same outside diameter, the 50 has a larger bore and thus less metal/weight).
You can load the same bullets in the 50 that you can the 45 with the right sabot(s) and use the same amount of powder, the myth of a flatter shooting 45 are just that, myth.
I bought into the supposed lesser recoil from the 45 but after researching, recoil is mainly a funcion of powder charge, bullet weight and gun weight. If the 50 can shoot saboted (or double saboted) 45 bullets of the same weight as the 45 can, and uses the same powder charge volume as the 45 does, and weighs nearly the same as the 50, how much less could it recoil???
My opinion is, the 45 will do the job that I wanted (whitetail) but in retrospect the 50 would have probably done that job (and countless others) better. Hindsight is 20/20 I guess.