They work fine. I used one for years with no problems. The powder in Steel shells burns dirty and it will gun up the 1100's gas system quicker than regular loads. Add a little water and you get a real mess.
The Beretta 390 / 3901 has a simple gas system that is very easy to maintain. One solid stainless piston. I dont know why they changed it in the 391. A solution in search of a problem I guess.