Been looking at a PWS/LWRC to run suppressed.  Why should I get a PWS/LWRC vs a 11.5" DI gun?

Will a piston be more reliable and be less prone to jamming?

Will a piston be more less prone to stove piping?

Well, pistons run cleaner, which helps offset the fact that suppressed rifles run dirtier, so in theory they should run more reliably (although I've never actually seen data that supports this and I suspect a quality upper like an LMT or a KAC will do great suppressed).  PWS also has an adjustable gas system with a setting for suppressed, which helps bleed off some the additional back pressure of running with a suppressor.   It also help mitigate some of the additional gas to the face you get when running suppressed.

I have an 11.5" PWS upper that I've just started running suppressed with a Dead Air Sandman S and it is the tits.

No, neither the LWRC or PWS will be "more reliable" or feed more reliably than a 11.5" from Colt, DD, Geissele, etc etc etc.

The only perk that those uppers will have is they come standard with an adjustable gas block.

Both LWRC and PWS make a cool rifle but neither of mine ran any cleaner than a conventional DI that was properly gassed. The excess fouling comes from the chamber, when using a silencer.

I will not comment on reliability of one over the other, as my DI and PWS rifles are both very reliable.  I have one PWS, a 14.5" P/W'ed and it shoots as smooth as you are going to find.  I shoot suppressed with Dead Air Sandman S, K and a Silencerco Omega with a KeyMo adaptor and all three work perfect.

IMO, if you are looking for a piston rifle, you cannot go wring with a PWS and I have a LMT piston rifle also....

As far as staying clean, IMO, the suppressed piston rifles are slightly cleaner than a DI after say 200-300 rounds....on a scale, if a DI is a dirty 10, the pistons will be a dirty 7 maybe 8