I think it has to do with the hunter, the style of the hunt, and the chosen area of the hunt.
For example, is the hunter in woods, meadows, or large fields? Is the quarry being stalked, or flushed, or is the hunter waiting in ambush? How far is the hunter walking in a day?
Will there be time to set up a tight position on a distant critter or will the critter likely be moving and be aware of our presence and the danger?
For me, with my 42" barrel on my .40. it has a straight walled, Green Mountain brand barrel. So that's pretty heavy compared to a swamped barrel. It's very nice to hold when standing, unsupported, as the "nose heavy" rifle tends to be pretty steady. I think if I was in a meadow I'd likely be OK taking a shot at a rabbit in the classic "offhand" or standing-unsupported position.
BUT..., I really don't like that position, and wouldn't do it in the woods as long as there was a tree nearby where I could use my off-hand flat against the tree, and my off-hand thumb as a "gun rest" for the rifle while sighting. That's highly stable, and one of my favorite positions. Full disclosure, IF the grass wasn't too high in my theoretical meadow with a rabbit presenting itself, or if I was on a high enough rise in the same situation, I'd likely use a tight, kneeling position, and be more sure of a stable sight picture. My rifle is positively NOT a rifle to swing on a fast nor even slow walking target. IF I engaged a walking deer, I'd have to set up with a sight picture ahead of the animal, and it would need to then cross my sights at some point. Sometimes this works quite well, and sometimes the spot I've picked turns out bad because the deer decided to change direction, and didn't cross in front of me... sometimes the squirrel on the ground is moving too fast when it comes into my chosen shooting spot.... oh well that's part of hunting, eh?
The "advantage" then is in my rifle is really the sight plane..., the distance between the front and rear sight making it much easier for my human eye to get a head shot on a squirrel, then ADD to that the overall weight of the barrel mitigates the already low recoil from the 90 grain round ball, and then ADD again the "nose heavy" aspect reducing the effect of recoil on my sight picture, helping with follow through.
OH and flintlock "long rifles" look cool. Other parts of the country may differ, but when I walk out of the woods with half a limit of squirrels or a couple rabbits, and a 42" flintlock, the reaction I get from the guys with modern, scoped rifles that see me is like the Hobbits being reunited with Gandalf..., and I'm Gandalf.
SURE..., I could have a rifle in .40 with a 24" barrel, that would shoot as well, perhaps better..., it would be easier to work with in thick brush, lighter to carry all day especially in an area with steep hills, and since I very much dislike shooting game in the offhand position, having the much lighter and well balanced rifle would not be bad since I don't want to use it offhand.
So from what I've seen, read, and done, it comes down to how and where one is hunting, and no matter the rifle style it has to be accurate.
LD