Jay Cunningham is right on the money. I get asked this all the time. My response is usually that there are a couple of hundred guys in the US military that "need" a piston gun, and they have them.
I have run my DI AR's in head to head very high round counts against piston guns without issue. In the most notable case, a Ken Elmore built Colt L/E 6920 ran 1920 rounds shot as fast as the users could pull the trigger (64 shooters hand the gun off) while doing an Aimpoint demo. This was run next to an HK416. The only difference was that my gun was hot around the barrel, and the HK wasn't. Other than that, neither gun had a malfunction or issue. The reality, is most of will never have 64 guys from one of the premier SWAT teams in the country lined up with a 30 round magazine in hand to burn through their gun (most of the internet genius's will never shoot this many rounds in the life of their gun). I do stuff like this regularly, and all with DI guns. I am currently using Centurion Arms guns with a CHF barrel that has the MG chrome lining and are mid length gas systems for my demo guns. My previous LMT MRP demo gun has 30,000 rounds of very abusive use and is rarely cleaned and has never had any major issues. Again......I need a piston because....? The key to running a DI gun, is running a top tier AR and stay away from hobby guns.
I do love my Steyr AUGs, so I have piston guns if I need them.