The 36 stays alot cleaner in the field, its hard to get it dirty and it doesn't foul with powder like the roller locked guns do. Also, it weighs alot less, weight was a big downfall of the 33--it makes it a smooth shooter with little recoil, but you wouldn't want to hump one around 12 hours a day for a couple of years. This is why they started making the "HK53" short barrel conversions, to try and lighten the gun so it could compete with the lighter M16 series. Also, the G36 is less expensive, which does matter--that's why the G41, which I think was the pinnacle of the roller locked guns, was ultimately a failure: it was a $2200 gun back when NIB Colt M16s were selling for $800 to military forces all over the world, and it really didn't do a whole lot that the 16 couldn't. The 36 is much more cost effective.