Traditionals are fine. No problems so long as you treat them right....
I've had one problem with traditionals. Its easily fixed. My traditional had a tendency to misfire. Then I discovered the culprit: After cleaning I'd oil the bore, set the gun in the cabinet, muzzle up as is traditional in most cabinets and safes. Oils would migrate down into the the little metal 'thimble' the nipple was threaded into. When I'd charge the barrel with powder, this powder would get wet with oils and I'd get a misfire or a hang fire. The fix was easy: Clean. Swab with oil. Run dry patch to remove most oils. Store muzzle DOWN on rag, so oils run down to muzzle, not breech. When its time to hunt, run dry patch again, snap a cap or two, then call it good - load up and hunt. This was a 100% fix for my misfires.....
Be careful on your muzzleloader choice.... Even those with side locks have two barrel twists. Fast twist, for conicals, often about 1 in 32 or faster for .50's. And slow twist, often on the order 1 in 60" for round balls. If you choose a slow twist rifle, you pretty much have to use round balls. A .50 round ball isn't as effective as a .50 conical/minie.... If you are going to go full on traditional and shoot patched round balls, a .54 cal would offer substantially better performance....