I’ve got a MK-XIX in all three standard calibers. I’ve also got an L5 in .357 Mag. I originally bought it with a 10” .44 barrel, which I had chopped and threaded for a silencer. Or I can screw a brake on it.
As noted, the .357 is really easy to shoot. The .44 is pretty mild as well. I bought the .50 barre last, since I figured the .44 would do about anything I would want.
The DE has a fairly high bore axis. It’s heavy enough that you don’t really notice it much in .357 or .44, but I find it tends to have a fair amount of muzzle flip with the .50 barrel. I expect the brake does more to reduce the flip than to reduce recoil.
I don’t believe I’ve ever shot the .50 indoors. The other two calibers are plenty loud there. I mostly shoot outdoors anyway.
The L5 is still a big gun. And the XIX is a brick next to it. I’ve only played with the L5 in .357, so I can’t comment on the other calibers.
The muzzle brake is interesting. The L5 feels pretty snappy. After shooting it, the XIX feels really sluggish when cycling. Kind of hard to describe. They just recoil differently from each other.