Well, yes, I think you are correct, although I'm not sure I buy the argument that a sensorless motor is inherently more efficient. The sensorless motor uses 'back EMF' to 'sense' where the rotor is, so the ESC still has to process 'sensored' info, so to speak. I think efficiency is going to be more a function of controller cost, regardless of type (sensored or sensorless).
But the issue you didn't mention is driveability. I think the jury is still out on just how sensored and sensorless motors compare on that issue. Many people seem to feel the Novak has achieved the driveability equivalent to that of a brushed motor (for racing). But not too many people have said the same about sensorless motors. That may also not be a function of motor type, but it's not clear as yet.
So, given the cost of the Novak system, and all it's nice features like an on-off switch, replaceable bearings, convenient packaging, resolderable wiring and a BEC that works under all load conditions, I'd say Novak put together a pretty decent product.