My thoughts on the LWRC........
I won't bother addressing the silly argument of which is better, GP or DI. Shoot what you want to shoot. I have no issues with DI guns of various lengths. They all work as designed and perform as expected. But I am not buying DPMS, Model 1 Sales, or Bushmasters either.
Where I like the GP design is for very short barrels and short suppressed barrels. Having a switchblock on a DI SBR is almost a requirement to get it running right. Suppressing a DI gun also fouls it fast and furious. Having the extra pressure and crap blown back into the action requires more frequent lubrication, and also requires cleaning at some point. I hate cleaning guns. I really do.
With the GP gun, less of that carbon and crap get blown back into the action, thus keeping it cleaner, longer. It is also much less sensitive to pressure changes from suppressed to un-suppressed and back.
In my very humble opinion, if you want a GP rifle, and cannot get your hands on a true 416, then LWRC is the way to go. LWRC did have some issues in their early days as a company, but once the employees bought out the shithead, they learned some fast lessons, and are now producing one of the top quality AR's on the market, and I would say THE best quality GP AR on the market. I have not seen, nor shot the new civilian version from Hk, so I cannot comment on that. The PSD is my only personal GP AR-type carbine, and (wait for it......wait for it......here it comes.......) it has been 100% reliable.
(Yay, another internet 100% reliable claim!!!)
Except it has been 100% over about 10,000 rounds of hard use, not 100 or 200 over the course of 5 years. One of my shooting buddies with 12" and 18" REPR's has put over 5k through each, and they are performing well.
I also have the SCAR, which is similar but different in terms of being GP operated. It works fine too. Probably only have about 6k through it. It did have a malfunction with a pre-production Tango Down mag a few years ago, but once I sent the mag back to Cahill and Company, the new ones have worked fine.
Both work great with the suppressor selected/used. It is the same suppressor for both guns.
The only thing that I find somewhat annoying is the piston in the LWRC. Because that piston is so hardened, it sounds like a tuning fork every time I shoot it. It sits and rings slightly from the vibrations. Most people don't notice it, and I won't notice when on the line with other shooters. But I also spend a lot of time shooting alone, and it can get to the point where it is like nails down a chalkboard. Especially during slow fire, accuracy practice.
Both the LWRC and SCAR are sub-MOA out to 100, though I run a 50/200 zero, and given the 4 MOA optic on each, I am pretty happy with 6 or 7" groups @ 200. Add to that, the effective range of the ammunition is about 50-85 yards, it is more than accurate enough for practical purposes. Both will feed a variety of ammunition reliably, though I shoot mainly 193, 855, and 262 through them with the occasional R2LP, and true Frangible. The recoil impulse on the LWRC is a little snappier than with a DI gun, but the SCAR is much more of a shove than a snap. Much like a 20 gauge semi-auto. The SCAR has a very soft recoil, and while it "feels" slower in cycling, it doesn't make a difference on speed drills against the clock. (The test bed drill where this became apparent is 30 rounds into a 3" circle at 7 yards, reload, and fire 1 more round in under 11 seconds)
I'm also a big fan of the 416, but given they are out of my price range for what I will spend on a hard use carbine, they can stay in the hands of those with too much money. Though, if I did own a 416, the pistol grip and buttstock would get canned immediately for something less bulky, and more streamlined. The 416 is also heavier than the same size LWRC.
I will buying another carbine this year.. For frame of reference, I own a LaRue Pred, 2 Noveske's, 2 Colt's, a Daniel Defense, the SCAR, and 2 AK's. LWRC is on the short list for this next carbine.
Hopefully that answered some of the questions from Lil' Lebo, and the BOM. And any others for that matter.