I've owned/still owned a few. By far the best was an LWRC 6.8 rifle. Just flawless in looks and function. Also have a Bushmaster factory piston gun...also works flawlessly. I've had a few conversion systems, too, and they've both been great though I haven't shot them much at all.

I worked the BM the hardest and actually abused the rifle by not lubing/cleaning it at all, ever, over maybe 3k to 5k rounds. Never failed and the majority of the shooting was done with Wolf or Silver Bear ammo. Actually, the only ammo other than Wolf or Sil Bear that I can really recall running through it was some 75gr TAP just to see if it'd work. It did.

I've seen no evidence of wear or "bolt carrier tipping" that some folks have experienced. Added weight is about the only drawback I can see...and having to modify certian handguards or rail systems to fit with the piston system installed.

Cleaning is a non-issue with piston guns in my experience. Wipe everything down and boresnake the bore. Lube. Done.

I can't comment on accuracy because I don't shoot for small groups at any particular distance. My gut tells me they're all very close, and in the case of the LWRC maybe more accurate, to what the DI guns will shoot.

I have a new conversion kit that I haven't tried yet that I'm anxious to try out made by made TNC or TWC or something like that. Looks to be of very good quality and I picked it up from a dealer at the Tanner show last Oct. He sold it to me for $245 out the door. I couldn't pass on that. Just haven't got around to installing it yet.

I'd recommend them (piston guns) if you don't mind paying the premium price.