I have owned (and still own, for that matter) a number of different M-Audio products. What they all have in common is that they have failed me somehow.
My first was a MIDI keyboard, which failed me in a faulty MIDI out port when I was going to connect it to my M50.
Second was the Firewire Solo audio interface, which failed me after a couple of years in that noise and glitching started to appear, both in the inputs and outputs.
Third was an expression pedal, which failed me just recently by spontaneously breaking, even though I hardly ever use it. As I was moving it around I heard something loose inside it. Turning it around a bit produced a plastic piece from its innards, and when I tried to hook it up to my synth there was no effect from activating it.
With this behind me, I have made the decision to try to avoid M-Audio as best as I can in the future. And I have found good replacements for two of the three products!
For the keyboard I went with Korg, once again. The expression pedal wasn't really worth replacing since I found I didn't really take it into use anyway... But for the audio interface I found a second-hand Presonus Firebox for a nice price!
Looking back I wish I had had the good sense to just get the Presonus from the start, since it's a better product in pretty much every aspect. More outputs, more inputs, better control of the audio signal in every way. The only little thing that I miss about the Firewire Solo was the M-Audio drivers which allowed you to set the audio level in software with the keyboard volume keys, but for the features I gain it's a small loss.