Yeah, I'll add in also. I've got a 12" POF P308 SBR and it's never really impressed me. I bought it, years ago, for the same reason as others, thinking that pistons would be superior to the standard DI system. I mean, it's still a nice little rifle. But I don't see any advantage over my Armalilte AR-10 12.5" SBR. The AR-10 shoots smoother also and is slightly lighter in the nose (obviously).
The DI vs Piston debate is similar to the Ford vs Chevy debate. It'll come down to personal preference.