[[[Way more power than a .357 MAX.]]]
That’s debatable. I can get 1850 with 180’s and about 2000 with 158’s out of a 10” Contender barrel rechambered by Mike Bellm with a true rifle throat not the bowl throats typical to factory barrels. Add about 150-175+ for each load in a 14” barrel. Both loads are very accurate and safe. You are shooting the Legend out of rifle barrels.
I can see the utility of the legend in that it is a rimless round suitable for semi-autos. Hence its current popularity. A gent was making 35 caliber rounds for the AR-15 out of 223 brass at one time. This eliminates that tedious work for sure.
You can get 2300-2400 fps with a 170 gr softpoint with the 350 Legend.
The 357 MAX operates at a max pressure of 40,000, the .350 Legend operates at max pressures of 55,000 psi.
It’s no contest.