Hi Nate
I've not tried running to units with one pedal board, so I'm not sure what the conflicts will be - a guess, based on common sense rather than actual experience would be that you'd run into problems with the control of the MPX G2 being about turning effects on and off within a patch and/or choosing patches, and the Repeater being about specific functions that are set - start/stop/loop/layer etc. It's probably possible, but you might be better off picking up a cheaper floor unit for the Repeater - Nobels have a few good cheap floor units that are worth checking out.
The MPX-G2 is a great unit, but it does have all the bells and whistles you could ever want - if you're not using them all then you're paying for stuff that you might not need. It's worth looking at the MPX-1 and seeing if that has what you need, also looking at the TC-Electronics G-Force and G-Major.
The MPX seems to me to be the rolls royce of bass/guitar processing - great sounds, very deep editting, easy control, and those fabulous Lexicon delays and reverbs.
The only possible problems are that there's no tube in it (a tube version of this box would seriously ROCK), and that some of the effects are a little glitchy for bass, especially the intellegent pitch function.
Also having heard what Michael Manring does with his, I'd recommend checking out the Boxx VF1 box - e-mail Michael about it, or ask Ed Friedland over at the musicplayer.com boards, cos they both get great sounds from it (and say hi to them both from me! :o)
I hope that was helpful
Steve
www.steve-lawson.co.uk