I beg to differ. The RoF cap was pretty slow, even with Rapid Fire attached it bugged me that the RoF was slower than the speed I was pressing the trigger was faster than the speed of the bullets coming out of the gun. The over-sampling would mess up my aim/cost me kills sometimes.
Cod 4 originally didn't have a ROF cap but they later patched one in iirc as people were using modded controllers.
Everyone is entitled to their own opinion, but in my opinion, the SMR is SO beast. Getting to level 10 was a pain, but once you get select fire....Goodnight. I run with Stock and Select Fire, 2 perk 1's and 2's. The only problem I have is running out of ammo because of massive kill streaks. Seriously, this gun hits so hard, but it's not a hardcore rusher gun. If you're patient and scope around corners, you kill enemies in 2 shots.. it's almost not even fair.