Yes, the general consensus is that they are unreliable.
Would that "general consensus" be from people who have lost on airball roulette?
At one time we had air ball roulette at all three of my "local" (within 100 miles) casinos but two of them have already been removed, mainly due to lack of play. The lack of play may have been caused by the unusually high minimums on it for the area.
I would hazard a guess as to the reasons for the slight variations in rotor speed to be able to counter those who use the various computers to time/track rotation. Simple solution to a perceived problem.
I would drop in on the machines from time to time while waiting for the wife to finish whatever it is she does on the slot machines and it was a usually an enjoyable 10 minutes or so. The differences in the rotor speeds were not noticible so for all practical purposes, it was a live wheel game with a timer set to launch.
Also, the lack of cheque handling was a big plus for me.