There are two "disadvantges" attendant to hunting with any muzzleloader, and they apply equally to all of them regardless of ignition type. One is slowness of a followup shot, if needed; the other is limited range (200 yards or less). I am so convinced that neither of these limitations is particularly serious, that I often hunt with a ML in regular season.

Properly maintained and loaded, even a sidelock suffers little. In wet weather you put a piece of plastic wrap over the muzzle and lock area, and even a flintlock is reliable. You CAN mount scopes on sidelocks, BTW, and some are every bit as accurate as any inline! Here's couple of Maxiball groups shot at 100 yards with a .45 and .50-caliber sidelock respectively, both scoped. Repeat shots can often be made FASTER with a sidelock, because capping them is easier than some of the bolt-action type inlines that have to have a 209 primer inserted into a hole in the breechplug inside the receiver opening.