I own a REC 7 that I got in December 2011, I've run about 1,000 rounds through it so far, what would you like to know about it? It's a real quality piece. The machine work, fit, finish, etc. are impeccable. The inside surfaces of the gun are as nicely finished as the outside.
The piston assembly is accessible at the front of the top rail. You push in a button on the front of the gas plug, flip small lever from left to right, pull out on the lever to remove the gas plug, tip the gun barrel down and the piston and rod fall out of the gun. No tools, no removal of the rail or other parts to get at the piston - just use your fingers and it comes apart. The rail system is a Daniel Defense and it comes with rail covers. The rail covers are marked "Daniel Defense" - but they're really made by Ergo Products. They're made from Santoprene which is a high temperature resistant thermoplastic rubber material.
It's functioned flawlessly. My only criticism is the trigger. From the factory it was 8 pounds. I ran 500 rounds through the gun to see if the trigger would ease up some - it didn't. I suppose if you're using the rifle in combat, crawling across the ground, or in a situation where you could hook the trigger on something with the selector on "Fire" - the heavy trigger might prevent an accidental discharge.
I don't plan on using my rifle in situations like that, so I changed the trigger to a Wilson Combat TTU-3G - problem solved.