The business of adding amplification to pit instruments has been around for some time. In my age-out year, my second, with Blue Devils in 1985, we toured with some equipment on loan from Yamaha (I think it was Yamaha... old brain cells) that included electronic keyboards and drums. The pit people mostly used it to play "Axel F" whenever they had a chance to plug the stuff in. I am guessing that it was packed with the drum gear. I am not sure if it survived the fire we had on tour to Madison. At any rate, there was discussion about this almost twenty years ago. I remember that it was a small issue in '79 or '80 with Ambassadors too as there was some debate wether true vibraphones, with the little rotating disc dohickys to effect vibrato, were legal on the field. The consensus at that time I believe was that if it had batteries it was not legal in ODCA or DCI.
We seem to have come a long way. Although I am an old geezer when it comes to rule changes, this one seems to have been considered for a long time and I suppose it should be given a chance.