Of course a shotgun is better than a 357 Sig. That's a no brainer. But to be honest, sounds like that shotgun article needs some serious updating. They sure haven't checked out some of the new 357 Sig ammo that is out there, and that LEO's are using.
The .40 and 357 Sig are two sides of a coin and work well together as long as the pistol can handle 40,000 psi. If you're thinking Glock, I'd get a Glock 357 and then buy an aftermarket barrel that has a little better chamber support.
If it's a SIG, it doesn't matter which one you buy. HK just supports the little USP compact in 357 Sig; Beretta just sells a small Cougar version of the 357 Sig as well. There are some aftermarket barrels for 1911 style pistols.
good luck.