I also hunt with a .50 and a .58. My first flintlock was a .54 Pennsylvania styled barn gun. It had a barrel from Green River Rifle Works, and was a good shooter. I don't own it any longer, and have no desire for another .54 caliber gun. I love the .50, and I love the .58; so there's just no desire for something in the middle.
My next gun was a .58 caliber Pennsylvania rifle; the first gun I built from a blank. It has a 42 inch Octagon to round barrel from Colerain, and a Bud Siler lock. I've taken three deer with that gun, and have not recovered a ball. With 70 grains of fff, and a .562 ball, it's a thumper! I still own that rifle, but I don't hunt with it these days. If I ever go after elk again, I'll use the .58. Or my 24 gauge Trade Gun.
My current hunting rifle is a .50 caliber iron mounted Southern Mountain Rifle, that I also built from a blank. Her name is Miss Sally. She has a 44 inch swamped Colerain barrel, in B weight; and a Jim Chambers Late Ketland lock. She's a nice slim rifle at about 7 1/2 pounds, and easy to carry in the field all day long. I've taken two deer with the .50. One with a previous flinter, and one with Miss Sally. One deer went down where he stood, and the other went about twenty feet. For our Northwest Whitetails, the .50 is entirely adequate. One ball quartered through most of the deer and exited. On the other I did recover the ball just under the hide, but it had passed through a lot of bone. My load for the .50 is 65 grains of fff Swiss, and a .490 cast ball.
My two cents.