The spawn for a different motor is by not getting people to accept it's ~$75 price when they see similar motors for $15 to $20. One of my reasons for the IO post. I know to be sure and catch that excessive IO on the cheap motors of the same KV.
I'll keep a watch on the 15T situation, but I don't mean to call you a liar.
It's so hard to convince me a plastic pinion is going to be reliable under that much stress. If it does, GREAT ! I repair and modify plastic injection machines. But I also do the same to CNC machines.
What works is what counts and the plastic will be one more chip off the weight.