I purchased my Encore as a 209x50 and have yet to purchase another barrel for it.
Mine is a stainless, but they should shoot the same. Here are some things I learned from working up loads for mine.
First, these things are capable of incredible accuracy. I worked up a load that I shot off of a bench that repeated 1" groups at 200 yards. My load was 80gr of T7 powder (not pellets) and a 240gr Dead Center by PR Bullet. Accuracy opened up shooting any more than 80 grains. My particular barrel did NOT like powerbelts. I couldn't get them to group satisfactory no matter what powder charge. I've since lowered the price per shot on mine since I only hunt with it (at fairly close range here in southern Indiana) and found the same 80gr of T7 powder and the Hornady 45cal XTP Mag sabot did quite well too, so that's my go-to load these days.
With pellets, there is a nice convenience factor, especially if you shoot in 50 grain increments, but there are some other considerations you need to keep in mind. The pellets have enough inconsistencies that you could be off several grains in a loading. Some are chipped or cracked, which also affects the charge or the burning characteristics. You also have to make sure you get a consistent seat against the pellets without crushing them. They are also considerably more expensive compared to loose powder. To me, these things outweight the convenience factor of the pellet. To get around this, I meter out an accurate charge of loose powder and drop it in a film case to carry in my pocket. It's just as quick and convenient as the pellet, but more precise and without all the other concerns you have to keep track of.
Another thing is getting a load worked up for best accuracy and efficiency in the barrel. Most barrels that length will not burn 100gr of powder before the bullet leaves the barrel, so you get lots of muzzle blast and more recoil without any real gains in velocity and a potential loss in accuracy. If you insist on using pellets, work up a load for your muzzleloader and then use the correct pellet charge as Deacon mentioned.
One last tidbit of advice is allowing the sabot to "ride the rifling" while you load. Once the sabot engages the rifling, let the rifling guide the sabot down the barrel by going slow and deliberately allowing the bullet to twist with the rifling. Shoving it down and jumping the rifling with the sabot lends to poor accuracy. Those little spin jag things seem to promote the same proceedure.
All of my whitetail hunting is done with a muzzleloader (except in bow season, of course!), and you're absolutely correct about them. I love the way they shoulder and point, and the accuracy is incredible as well as long as you take the time to work up a good load for it. Congrats on a great purchase! Both set-ups look sweet!
