Guess I'd call myself 'practical' if not 'modern practical'.
This is because:
I've noticed my sidelock percussion guns are easier to clean than my inlines.
I've noticed that the patched roundball is an especially effective deer killer and has done a better job for me than either saboted pistol bullets or conicals.
I've noticed it's MUCH easier to get consistently good accuracy with a PRB in a slow twist barrel than it is to get the same shooting saboted pistol bullets or conicals in a fast twist barrel.
I've noticed practical field accuracy holds up over a much longer string of shots when a moderate load of loose powder is used instead of a magnum load of either pellets or loose powder.
I've noticed that shorter, carbine length rifles work better out of a ground blind than either long-stemmed traditionals or modern inlines with 4" or 5" of spring-loaded gizmo before the barrel begins.
I've noticed that lead round balls and cloth patches are much cheaper than pistol bullets and sabots.
I've noticed that over the ranges that a muzzleloader can be relied on, either open sights or, better yet, aperture sights are preferable to a scope.
I've noticed the larger the bullet hole(s), the faster the deer expires, the less he runs, the easier the tracking, and the shorter the drag.
So my ideal 'practical' muzzleloader is:
A .54 percussion sidelock which will shoot Patched Round Balls accurately with a barrel 21" to 26" long, peep sights, and loaded with no more than 90 gr. of powder. Prosaic but effective.
YMMV
ETA: OTOH, I own several rifles that fail to meet this ideal that I still enjoy shooting and hunting with.