I have a SL upper on my old Bushmaster lower, mainly b/c I cant hump a heavy rifle. Having said that, and knowing what I know now, I shuld have bought one years ago. Teh SL shoots 2" groups at 100 yds with my old eyes and issue sights, weighs less than a Carbon 15, and holds POI even when the oil is smoking off the barrel from the heat. The only downside, as mentioned above, is that it does 'het up' in a hurry.
It's great for 3 gun or other tactical shooting due to its balance, wich is almost centered on the mag well, unlike the front-heavy HBARs. If you plan on 3 gun where you may be using volume fire, it may be worthwhile to install M4 handguards for the double heat shields. I ran a 3 day long carbine course with mine, and not even ONE hiccup that was not operator induced. I think that you will really like it.
Gratoutitous pic:
Ops