Mainstage or Loop machine?

I am looking into the purchase of a looping machine, i.e. Boss RC-300 , just to be able to make music quicker and then transport it to Logic to add more and edit etc.

I have read some reviews about mainstage - will this be equally as good? And does it have to be used in conjunction with logic?

Finally if I do get a looping machine like the Boss rc 300, how would this connect to an m-audio fast track ultra interface, for recording in logic as well as playback though monitors?