I am just trying to fully understand the compromises for each length. The give and take.
Back Home, Years Ago, I bought my brother a 16" Winchester Trapper in .45 Colt. Although I'm not a fan of the Winchester action, that rifle quickly became my favorite knockabout rifle... I 'borrowed' it from him when I was camping, or out in the mountains, and we carried it on the tractor when we were working his property. I paired it with a Ruger Vaquero in .45 Colt, so it could take the same 'Ruger only' loads the rifle did.
About 20 years ago, I bought a Marlin 1894FG... the reissue of the .41MAG 1894C... with a 20" barrel. I immediately started investigating having the barrel and mag whacked to 16" mostly because of how handy the Trapper was, and because a real 16" Marlin .41 was, virtually, Unobtanium. It never came to fruition... and I'm kind of glad. Some years ago, I started shooting steel pipe at long ranges... and the 20" barrel of the Marlin got me out to 600yds with some ease, and with good success. Friend of mine was trying the same thing... with, of all things, a 16" Winchester Trapper in .45 Colt... he was limited to 200yds, with a lucky shot here and there at 300yds. Granted, he was shooting lower velocity factory ammos, with heavier (255grn) bullets, vs my 215grn bullets pushed by IMR4227. That is an extreme example, however.
The 20" Marlin isn't that much more 'unhandy' than the 16" Winchester... it's only 4" and probably a pound or two more, loaded.... but there is no denying the 16" barrel is handier. If your shots are made within 150yds, with the .44MAG, I don't see any benefit to the extra 4". I shoot receiver-mounted peeps on my levers, so I negate a little of the lost sight radius, and I just shoot peeps better than open sights... something to consider. I am not a fan of a tang sight on a field rifle... there is too much potential for damage, and it can be awkward to use in a hurry... but that is just my .02.
If you are shooting mid-range .44's, there is virtually no difference in 16" vs 20", but if you are shooting full-house .44MAG loads, and wanting the most velocity... the 20" is your answer. Powder choice makes a difference, here.
My standard Unique load, between my 4" .41 and my 20" Marlin is only 200-220fps.
My standard heavy load, using W296, it's 520fps. The estimated difference between a 20" barrel, vs a 16" barrel is only 75fps, using QuickLoad.
At the end of the day, it depends on your greater purpose for the firearm.