I don't claim to be an expert in this field so, take my likes and dislikes in their context. I still like the RPR and intend to get one. I don't like the buttstock and never have. Yes, it appears easily adjustable and that's good. But everything is hanging out in the open, subject to dust, impact, snagging, etc. In short, it appears good for the bench to me, but not so much if you are going out in the dirt. We had one in the store recently that I missed out on. Too slow, not enough spare $$ at the time. It had a Magpul PRS stock. .308. Everyone talks great stuff about the 6.5, but I don't have a ready source for the ammo and I don't handload it. Is it available commercially?
The looseness of the folding stock doesn't sound good, but what the blog didn't say was how often the stock was folded. If it was folded on a frequent basis, I could see friction causing it and one might have to consider whether you need to fold it as much...while waiting for the fix/upgrade. If the play developed just from shooting the rifle without frequent folding, that's a more significant issue to me, and one that should have been caught before releasing the rifle for sale. I'll keep an eye out for more reviews and see if it crops up elsewhere.
I have never looked at the handguard for off center and flex. I have a long Troy rail on a 20" AR and it will flex without a lot of force. I originally had a front sight on the rail and rail issues made it a no go. I cut a notch in the top and reinstalled the standard FSB. Different rifle, but I was taking a class one time and had a Harris bipod mounted on the forend I thought it would be an asset when shooting under time at 200yds. At the buzzer, drop to prone, get your shots. What I found, was that if I wasn't dead on with the bipod and had to load it slightly to one side or another, the shots would spread horizontally. I think it was due to torquing on the bipod and how it affected the recoil impulse angle. This seems similar to what the blog references with handguard alignment and flex.
Snipershide did another review and also changed out some stuff. PRS stock, LRI barrel, handguard and bolt shroud, Magpul grip, Seekins safety. Start counting on your fingers and they kept the receiver, bolt, trigger group and the lower receiver/magwell. Great groups, but I thought the point of the RPR is that you didn't have to do all that?
Barrel changes appear straight forward, but I need to find out about the receiver blocks for the action. Get your go/no go gauges and you're good to go.