I have no doubt 45 caliber in-lines have faster muzzle velocities and flatter trajectory Headhunter. But considering my average MZ shot distance is 32 yards - basically bow-range - I prefer to hit them hard and drive a big hole through them, even if my big bullets drop like a rock after 75 yards.
I also have no personal experience with 45 caliber sabotted pistol rounds out of 50 caliber in-lines. I just don't like the idea of losing caliber and penetration by going with a smaller, lighter, faster bullet.
Average shot is 32 yards? Be interested to know where does that data come from? And "hit hard and drive a big hole", deer rarely take a step when I shoot them with any one of the 3 muzzleloaders I own in 45. I cannot remember one going more than 20 yards, and it rare that they take more than a few steps and I have killed deer from point blank range out to 260 yards with a muzzleloader. I have also killed a "few" deer with a muzzleloader. Actually to me, a muzzleloader are not much different than shooting a deer with one of my proverbial "cannons", I have couple rifles in 7MMSTW and a 26 Nosler, actually deer have ran further with my rifles than any ever with my muzzleloaders. Depending on bullet type, I have seen exit holes from my rifle big enough to drop a softball in and a couple deer still ran over 100 yards, one doe, most of a lung was hanging out of the exit hole and she still ran close to 150 yards.
To me the average shot distance means nothing. I hunt in places where my longest shot, even with a gun, may be 50 yards or less, I also hunt in places where my longest shot will be however far I can accurately shoot. In November, I try to be where I can see as much as I can and for sure a 100 to 150 yard shot is not out of the realm of possibility even on the public land I hunt and a couple of the public places a rifle is not allowed. Next weekend in KY, I can see 300 in one direction and 400 in the other, yep, I am going to shoot and be prepared to take the longest shot I can, which with my new muzzleloader should be 300, I will know for sure after today.
If I hunt with traditional, it will be open sights and longest shot I have made was 107 yards and that is 7 yards beyond what I feel like should be my max.
If I hunt with "modern", I am going to max out not only knock down ability, but also distance to cleanly kill a deer, not that it matters to anyone but me, and I see nothing wrong with a 50 ( I think in some states it is illegal to hunt with a caliber smaller than 50, they may also be traditional only), but IMO it is hard to beat a 45 for "knock down power and distance", especially for deer.