I've built a few piston rifles, back before everyone had it figured out. There were some good conversion units and some bad ones. The bad ones are no longer made and only the good ones continue to be manufactured. I've run piston conversions by Osprey, Adams Arms, Ares and PWS. The PWS is not a "BAD" system, but it has more mass than the others, so it recoils just a bit more than the others. My current rifle uses the out-of production Ares GXR-35 Black Lightning conversion, which they stopped selling in 2015 to focus on the Shrike and other projects. If it ever has a problem, I'll probably be SOL for replacement parts, but it has troopered on for over 10 years now. The only problem I ever had was that my kit was sold back before folks figured out how to fix "carrier tilt" where the back end of the carrier was hitting the front edge of the buffer tube. Current piston carriers have rounded bulbous dimensions at the rear end to ensure the carrier doesn't catch the buffer tube and chew it up or jam. Another solution, for those like me who had an older carrier with traditional (original) dimensions like that of the DI carrier, was the new buffer tube with a slight extension around and forward of the buffer stop, so that the carrier was never fully forward of the tube, and if it tilted, tilted downward onto the buffer tube and could not jam up. I got one made by POF that they use on their own rifles, and my old Ares piston conversion has never caused me grief since.
There are 2 main reasons I am a convert to pistons over DI;...insensitivity to ammo variances and cleanliness/reliability.
Now if you always have proper ammo and proper lube, neither of these should matter. But as the ammo droughts of the last 20 years have shown us, the ammo supply chain is fragile and you have to be prepared to use whatever crappy ammo you might have access to. How many of you experienced TULA steel cased .223 failing to operate reliably in DI carbine length gas systems? That was the failure of TULA using a powder with a burn rate that was inappropriate for the DI carbine gas port locations. But that same ammo fed into any .223 AK or piston-driven AR cycled just fine. Likewise, while CLP or BreakFree or many other gun oils will keep a DI AR rifle chugging along, plain old WD40 will actually absorb all that carbon and crud like clay and start gumming up the rifle. This is because the DI is puking into itself. But on a piston gun, your selection of lubricants is not so potentially fatal as that. I've run my piston rifle with WD40 for thousands of rounds without a hiccup. I've seen DI guns start to short-stroke due to gumming up with WD40 sludge after only 250 rounds, depending on the propellant of a given loading.
Do piston ARs recoil more than a DI rifle? Negligibly, yes. The difference is minor. We are talking mere 5.56 after all, which doesn't recoil that much to begin with. And on larger calibers in AR10 types, the difference is even less noticeable.