Scott, the lower level PSRs have a slight glitch when the footpedal is depressed, shutting off the vocal signal for a split second before the harmony is applied. I've tried 3 or 4 different types of pedals and the result is the same.

My trademark sound has always been a "Four Freshman", "Eagles" type vocal group and it's important for me to turn harmonies on and off mid word, mid phrase, or any old time I think it's appropriate ... the 910 makes this impossible for me, and therefore limits my creativity during a vocal performance ... which is EVERY performance, just about. I play very few instrumentals.

I never got the 910 to recognize the MP3 files I had on my USB stick either, but by then I already knew it was going back. I'm sure for $4000, the T4 put a little more thought into the hardware issues. The 910 is a great entry level instrument, and an "OK" mic input, but the harmonizer is so far behind the pack. That's only my opinion, of course, and I have a very strict design for my vocals - it's 90% of my show.