To be honest, the EOtech came off, and a 1.5-4.5X scope went on that rifle for my first range test. (testing for accuracy) What I found was that the top rail barely got hot at all. I did some slow fire, then later so improvised drills (rapid fire a couple of mags) I expected that the rails would get uncofortable, but was suprised to find that the top rail was only warm near the FSB, and the FSB/barrel were too hot to touch. I have never used the original RIS/RAS, but I'd assume that with metal to metal contact at the Handguard cap/FSB, that thing would be much hotter than the RASII. Over all I was very impressed with the unit.
Furet, with an EOTech, taclight, 2 loaded/cinched mags and the heavy bushy barrel it is a bit weighty up front, but its not too bad.
Tex78