.357 Sig is a very high pressure cartridge, at a SAAMI mean peak pressure of 40,000 psi... higher than .40 S&W (35,000 psi) or even 10mm Auto (37,500 psi).
Faster jacketed bullets tend to wear out a barrel faster than slower jacketed bullets. 125gr @1,400+ ft/sec will wear out a barrel faster than, say, 155gr @ 1,200 ft/sec.
And finally, it is just plain more powerful than most .40 S&W loads. And while practice ammo for .40 S&W often consists of mild 180gr subsonic loads, .357 Sig practice ammo is typically still running at 1,350+ ft/sec.
So it wouldn't surprise me if a .357 Sig handgun tended to wear out faster than a comparable .40 S&W handgun. Bottom line is, there is no free ride, especially considering that .357 Sig guns are all just re-barreled .40 S&W guns, that in turn were (mostly) re-barreled 9x19 guns. Accelerated wear should be expected, though it probalby wouldn't be drastic.