I've had one since '02 or '03, can't recall when I got it. It's a great carbine, and it's probably RRA's most popular model. Mine has the standard trigger rather than the 2-stage, but the 2-stage is rather nice! I went for the chrome lining and the Hogue grip as factory options. I later dicthed the carry handle and went with an ARMS #40 flip-up rear sight, added an Aimpoint Comp ML2 in the Aimpoint QRP mount, and slung it up with the Specter Gear SOP sling. I recently added the Command Arms Accessories stock saddle, and it was the best $20 I ever spent. It provides a much better cheek weld when the stock is in the closed or "one out" position, and it has waterproof compartments for batteries.
I decided against a quad rail system, b/c I'll probably never mount a flashlight, I don't have a need for a tacticool forward grip, and I don't use infra red illuminators or lasers. A lot of people get them b/c they just look cool, but that goes against my beliefs in firearms systems. I am a big proponent of only adding what you need and will use. Larry Vickers wrote an excellent article a few months back about this very topic.
I would say to go for the chrome lining, and the 2-stage trigger. Anything else is entirely up to you. I love my setup and noone can convince me that I need to hang more crap off of it! :???: Mine still has the fake flash hider on it. I decided to shoot the barrel to death and then go from there. I like the idea of a 16" over a 14.5" with permanently attached flash hider. Gives you a little more effective range.