I own and shoot both kinds but, more and more, my preference is the flinters.
As others have said, there is a learning period where you need to figure out how your gun works best. That is true of both ignition styles. Probably easier to do with the caplocks. In the long run I find there is less fiddling with my flinters.
The flintlocks have a bit more fiddling at the start, but once you get to know the gun and get it set up right all you need to do is check a few small things like flint sharpness, position, tight ness in the jaws, and a clean touch hole. With the caplocks you are forever fiddling around with them little bitty caps.
You will get the occasional klatch, flash-in-the-pan, or hangfire with a flintlock. Those problems will be minimal if you do your part and check the things I mentioned earlier.
You will get the occasional missfire with a caplock too. Bad or weak caps, junk in the fire channel, etc.
If you run out of flints you can probably find a rock that will spark. You'll rarely find a tin of caps lying on the ground. :wink:
Whichever type you use your feet will still get cold in the winter. :haha:
I shoot in temps ranging from 100+ to twenty or so - degrees F. I don't think winter really cares which ignition type you use. Maybe if it ever gets so cold the sparks freeze in mid air... :haha:
Rain can wet the prime in a flinter or the stuff in a cap. I keep my muzzle down and my lock covered when hunting in the rain. A bit of tallow or greasy lube around the very edge of the pan will help keep your prime dry when it really pours. Not that big of a deal really. I have hunted all day in rain and snow, even blizzard conditions.
There is a certain mystique that flinters have that I just don't find in the caplocks. A longrifle just seems to me like it should be a flinter. Plains style half-stock guns just seem more "right" to me with a caplock tho. That is just my personal opinion, both styles of rifles were built with both styles of lock.
Another thing that needs consideration is whether you desire to portray a particular era. Pre-1830's personas need flintlocks. If you plan to join a group there may be restrictions too.
Some folks never do like flint, others never like percussion. You should try both if possible and decide which is best for you.
Here's a few ML hunting pics:
Caplocks; (my best 2 bucks ever, all weapons, were taken with caplocks)
And a few with the flinters;