If it helps, I've had both the MF101 and the Xerograph. They are both great pedals.
To me the MF101 was a bit more natural/less synthy sounding, which can be great. It's also very easy to get nice useable sounds from. Noise was never an issue for me, like Luke says, it's fine live.
The Xerograph is a bit more unwieldy. The oscillating squeals and resonance boost can be absolutely brutal, so you need to be a bit more careful. With care though, you can get some lovely settings which are a bit more synthy than the MF101 IMO.
I now use a Xerograph because it's smaller, easy to power, and sounds great. If I was twiddling settings on the gig, and had no space constraints, I'd happily use the MF101, even if it is a bit more 'polite'.