My modern, in-line muzzleloader has precisely
ZERO (0) advantage over a traditional arm, IMO.
My rifle happens to be a T/C Encore, the new Prohunter model. But no matter how advanced the design, or how many high-tech materials and methods are used in it's manufacture, it STILL loads from the front. And blackpowder ballistics are blackpowder ballistics. You can only get so much performance out of charcoal!
My rifle happens to shoot great with real GOEX FFg, thank you very much.
The clincher for me is that the Encore fits me and feels better than any of the old-style sidehammers (and I've fired a few and own one, albeit a cheap one). If a Hawken was as comfortable to me, I probably would have bought it instead.
I will never look down on anybody shooting an inline, nor will I consider it a huge advantage over a more traditional system. And those 150gr loads the manufacturers tout? I'll pass thank you. 100-110gr of loose Pyrodex RS or GOEX 2f is all I need.
Good luck and good shooting, no matter what your preference is!