i concur.
if you paid a great deal for it, this doesn't mean that it's a high quality item and, by the same token, buying some thing without a humongous price tag doesn't necessarily mean it's badly made.
i have always been a fan of Thompson Center, based on their reputation and demonstrated guarantee: no quibble, no question, send it in and they replace it by return mail. i'm given to understand that they've changed hands, so i don't know if the guarantee will still be as good.
for this reason, i'd go with a used Lyman GPR, in .54 if you can get it.
You may also want to consider buying Dutch Schoultz' monograph on muzzleloading accuracy
http://www.blackpowderrifleaccuracy.com/
this was a great help to me and i recommend it to your use.
good luck, and if you ever have any questions, you're in the right place!
make good smoke!
p.s. - there's a Lyman GPR in 50 cal on the auction page of the forum... just a thought...