After nearly forty years I still find working with more than one camera at a time (during the course of a 'shoot') to be unproductive and distracting from the task at hand. Go out with one camera, and whatever camera that is will dictate the ranking of the rest.
Originally Posted by EASmithV
But you don't need to unload equipment to clear your head, just put it away in a drawer and forget you have it. Use your large format or digital to exhaustion and when you feel like a re-fresher go to the drawer and see if whatever you take out can add to the work you have in mind. Going from 4x5 to 6x6 can be fun, but equally it can remind you why you went with 4x5 in the first place, and visa versa. So don't rule anything out, but concentrate on one format/camera as the datum point from which others are judged.