I have a PWS and believe it's more a battle rifle, but mine has a 14.5" barrel. I have heard of more people using the rifles I suggested for precision work. Doesn't mean the others can't. Keep in mind if you go POF I believe it isn't compatible and it'll have to be a complete rifle, same with the LWRC. Not so sure on the LMT, but FarKle has one, ask him what he's wrung out of it.
All in all I'm not sold on the piston set up and won't do it again on an AR rifle. DI works, well, and I clean my rifles. Can't imagine I'd ever shoot so much it's an issue in one range session