I purchased the MP-500 to use as an interface for acoustic guitar and vocals with a laptop running Ableton Live. My goal was to use the footswitches to toggle various effects within Live, and the main reason that I bought the MP-500 over the XSonic XTone Pro is because the MP-500 has two expression pedal inputs rather than just one. I also thought that the two-tiered, angled switches would provide some usability improvement over the XTone, but in practice, neither of these features really panned out.
The switches are a bit too close together, making it difficult to press the number rows without also hitting the associated letter (i.e. it's difficult to stomp on 2 without also stomping on B).
The deal-breaker that I hit, though, is that the switches themselves can only be programmed as Toggle: On or Toggle: Off.
When Toggle is on, the switch behaves like a completely reasonable toggle: pressing a switch once sends a CC value of 64 to indicate that the switch is "on", and pressing the switch again sends a CC value of 0 to indicate that the switch is "off".
Unfortunately, when Toggle is off, the switch only transmits a CC value of 64 on press, and does not transmit any CC value at all when the switch is released, which makes it impossible to use for momentary effects (e.g. raise the Send amount to 0dB when the switch is activated, and drop the Send amount down to -infinity dB when the switch is released).
For typical stompbox emulation, this might not be a deal-breaker, but for my uses, it renders the pedal inadequate.
Further, I could not figure out how to get the output of a Roland EV-5 expression pedal to register with the MP-500 at all, in either of the expression input jacks, so the benefit of having two jacks was also quickly washed away.
It's unfortunate, because the form factor is relatively unique, and the feature set is extremely close to what I actually need, but the execution didn't deliver.
