I would think if they were using 3 speeds in other bikes there'd sure to be a few 3 speed Maico's?
After riding an AW440 for my first time a couple of weeks ago, I'd agree that the power spread would be wide enough BUT the vibration in the higher revs would rule-out any benefits of a 3 speed 501.
I have never owned or ridden a 501. The earlier full cheek crank 440's are notorious for their vibration woes, easily fixed though, even without going to crank balancing specialist.
The 501 crank has LARGE cheeks with a much much smaller stroke than all the other open class Maicos.
Just those two prerequisites alone make for a much more harmonious outcome.
By the way......I've never heard of a 3 speed 501
Neither have I.
I wonder if its just a case of "It only needs three gears" because most of them are actually wide ratio trannies with the power delivery having a very wide spread.
I know from racing and vinduroing the 84 XR500re, that it only needs three gears, just like the Beezza's.
In fact in the Spare XR's diet the first things gone are 4th and 5th gears and components and I am going down one tooth or two on the rear depending on the track.