I would imagine you will not have a problem of any great significance. The position of the motor on the MMF-5 and similar models is indeed a little unfortunate, since the cartridge gets closer and closer to the motor while the record plays. I would think the MMF-7.1's motor location does help.

Also, the MMF-5 was straight 120V with no wall wart. I think the low-voltage wall wart dramatically reduces the field around the motor. Your odds of a problem are probably quite low. AK member Puma Cat said a Sonata hummed on his Rega P5, which does use a low voltage motor (not 120V). But I don't know if it was this issue with AC motors or if he had a ground loop issue.