The G11 didn't have to eject the casings, so it was capable of firing said 2000 rpm in 3 round mode. And the G11 was a working concept. A very GOOD working concept. The only reason it was never implemented was because the Cold War pretty well ended, resulting in massive military budget cuts, so instead of buying an entirely new system and ammo, they decided to wait for later.
In 1998 I believe they tried again, with candidates like the Steyr ACR. Then the US military decided to go with the OICW, but that fell out of favor due to A) Weight , B) Maintenence (They claimed the weapon was 100% sealed. According to some people i've talked to, they still managed to get dirt into it and screw it up), and C) Ammo cost for the grenade rounds (6 dollars a pop). Of course they still plan to use it is a grenadier weapon, but not as a general infantry weapon. And, of course, the XM8 is undergoing trials now.
Sorry for the little rant.