I don't know but I would guess that the higher the quality the less wear and tear the machine will experience. Yes, the cut motor will work longer and wear the brushes sooner but my understanding is that he higher quality translates into narrower passes and less wood removed with each pass. That, I would think would be easier on the flex shaft and the spindle bearings and probably the y truck motor, etc.
Just my thoughts and worth every penny you paid for them.