There is nothing wrong with a T/C Encore at all. As you stated, it does give you the ability to change barrels out and make the rifle into a number of calibers. Actually if I had no, or few rifles, I might even go that route. The thing you need to consider is the warranty, customer satisfaction, and over all performance. I think the Encore (since you like that idea of changing barrels) a very good choice.

If you want just a muzzleloader, then you could look at a number of different rifles out there. The T/C Triumph & Omega, the Knight Rolling Block, and the new KP-1 if it ever gets out on the market, as that is another rifle you can change out barrels to make different rifles.

If you go traditional then go with a .54 caliber if possible. I would look at a Lyman Great Plains & Trade Rifleor a T/C Big Bore in .54 or .58 caliber.