Why don't you consider a NEF Handi-Rifle/Huntsman. They are a really nice outfit for the money. The NEF Sidekick Stainless I had would practically put shots into the same hole at 100yds with the right load. I think your chances of getting an accurate rifle are MUCH better with the NEF vs. the CVA.
Concerning CVA vs. T/C. CERTAINLY T/C isn't the only muzzleloading game in town. But they are a GOOD one, you can bet on that. You specified that you are wanting an interchangeable barrel system. Well, that limits the possibilities. T/C offers one of the better systems. They ARE a little pricey. HOWEVER...you are practically ASSURED of a more accurate rifle, better resale value, and better customer service. The CVA Optima Elites are unproven in the centerfire realm. And quite frankly, their muzzleloaders are a hit or miss proposition. Most seem to either get one that shoots GREAT or get one that won't group at all(as in my case). The other less-expensive alternative to the Encore is the NEF HandiRifle/Huntsman. You have a MUCH better chance here of getting a good rifle! Most that I have heard from are getting really good accuracy with their muzzleloaders and rifles on the NEF frame.
Be assured that the reason a LOT of folks recommend AGAINST a CVA is for a reason, not just because they enjoy picking on CVA..