Just so I'll know, which Suzy has a completely NEW engine. What does it have that the Bandit engine doesn't. Hey, I don't know and I'm not a mechanic.
The sport bikes get all-new engines every 2-4 years. From what I've been reading, the '06 GSXR 600 & 750 will have all-new lumps. The hypersport bikes have to do this to stay on top of the competition. Sporting standards, like the Bandit, don't need to do that. What they have the Bandit doesn't is everything is made as light as possible to reduce rotating mass and lower overall weight. They have pistons with almost no skirts, running in water-cooled blocks with holes in the lower part of the cylinder walls to reduce pumping pressures on the bottom end, titanium valves, fuel injection, and so on...
I predict the new GSR600 phasing out the Bandit 600/650 and a new liter or liter-plus class GSR using either a GSXR1000 or GSX1300R based engine appearing in '07 to do likewise to the B12. While the new 3G B12 has a few improvements over the 2G, it doesn't seem like handling or power improvements are part of the deal, so it will continue to loose out in magazine shoot-outs to more up-to-date bikes like the new 2G FZ1.