No interfernce of any type. Matter of fact, we often play in a venue that has a T-coil system that transmits wirelessly to suitably equipped hearing aids. It drives many other pickups (and amps) nuts, but the M1A just chugs along completely unaffected.
I also didn't care for the looks at first, but I've really grown fond of the looks now. I bought the J45 for $25 in 1973 with both the top and back TOTALLY smashed. I had it rebuilt and the luthier finished the top in a truly unique design. The white M1A dramatically adds to the unique one-of-a-kind appearance.
Since "great sound" is very subjective, I really hesitate to recommend what sounds good to me, but I am a HUGE fan of the M1A. I flat pick only and run the M1A thru a TC Helicon Harmony G then straight into the mixer and house system with a touch of reverb.
Possibly your local music store could slip on in your J45 for a trial....but, for me, the key is adjusting the pole pieces to get the sound you like.