the reason I'm asking is because I was wondering how many effects would you need to use simultaneously. for instance, if you need more than one modulation effect (chorus, phaser, tremolo, etc) for one sound, it'd probably be best to go for the M13. and it does indeed seem to be pretty functional for live switching too.
but, for recording, my favorite multi-fx unit would be the Boss ME-50. but for live settings, despite the sound quality, you can't turn the distortion off at the very same time you turn the modulation effect on, 'cause you'd go into tuner mode.
so back to the other issue, in the ME-50, the harmonist function, tremolo, phaser and stuff are all under the "MOD" section... it's not uncommon for me to use two or more of these effects simultaneously, so if you're like me, you're better off with something else.