I just bought the .357 lightweight L5 version, which has a shorter barrel and integral brake. It does make a noticeable difference shooting it next to the standard .357 MK-XIX. And generally the larger calibers benefit mote from a brake.
I pit a brake on a .44 barrel back before they started doing factory brakes. That one cuts out around half of the muzzle flip, and I expect one on the .50 would do the same.
Initially, MRI started with a bolt-on brake that extended the original barrel, giving you an equivalent 7" barrel. More recently they started machining the brake directly into the barrel, keeping the overall length to 6". I like the looks of these better, but it's a matter of personal preference.
Here's the .357 L5 and the standard 6" .357:
Desert Eagle .357 comparison: L5 vs. MK-XIX
And here's a few other comparisons:
Desert Eagle .357/.44/.50 Recoil Comparison
I've thought about getting the .50 barrel Mag-Na-Ported, but haven't yet. It would be interesting to see the difference between that and a factory ported barrel.