fwiw - a close friend of mine is a pro-mech for a team that used Rotor PMs last year - he said that even with the extra support they got as a premium-sponsored-team, their PMs were a living nightmare.
Wouldn't calibrate, wouldn't hold calibration, weren't stable...
he's still with that team, so I'm afraid I can't get into other details that would incriminate him... but I'd recommend on giving them a pass unless their units start getting vastly better engineering.