I think a more-appropriate name for the Fazer/FZX based upon the design of the engine, would be the baby FZR. Both (Fazer/FZX and the FZR 1000) are severely-inclined forward, inline fours with downdraft carburetion, and despite spotting the VMX-12 VMax about 25% more displacement, the five-valve Genesis FZR 1000 engine actually out-powers the VMax, and is a bit over 470 lbs, vs the VMax at 590 lbs., so ~20% lighter. Given those statistics, it's easy to surmise who wins that contest. The FZR 750 was the same chassis and etc as the FZR 1000, just a smaller engine, for Superbike class racing in the AMA (it came with better forks and rear monoshock, -Ohlins-and was actually more-expensive than the FZR 1000). One advantage the FZR 750 had, was a six-speed gearbox, but the factory eliminated the six-speed for the larger bike, because of longevity, as the five gearsets could be made wider than six, in the same case. Some people have fitted the six-speed gearset into the FZR 1000. I still have an FZR 1000, 1987 model, I bought from a friend in '88. He was the original owner.
The FZR 1000 was a 'first' for Yamaha and the industry. While there were bikes with aluminum frames before this, the FZR 1000 was the first production bike to have a perimeter box-section large-diameter aluminum frame. Compared to the Suzuki GSXR 750/1100, it made the Suzuki 'slingshot' aluminum frame, appear puny by comparison. The FZR 750/1000 was also the first modern production bike to use five valves: three intake and two exhaust. This cut-down on valvetrain weight, and allowed more valve area and a higher rev-band redline. The FZR 750/1000 also ran radials, one of the first bikes to have this spec from Japan.