Thanks for the kind words about my rifle 8200 rpm. With a full 30 round mag it weighs 6.5lbs!
Personally I love a light barrel. Heavy barrels are good on target rifles(heavy in the front is more stable for offhand shooting) and sustained fire full auto weapons, but they hurt the balance of the weapon, making it tiresome to carry all day, and they are slower in a CQB environment.
I have run through 300 rounds as fast as I could load, get the sights on target and pull the trigger. I had to wear Nomex gloves just to hold on to the handguard (I wear these anyway, been burned by many an AK, AR and FAL!), but the point of impact did not shift dramatically enough to cause any rounds to miss a 1/2 size torso target at 100m. I am sold on light barrels for semi-auto fighting rifles.