I think with the large differences in gathering favor and so as a result, the difference in the importance of MU's to civilizations of different cultures... (takes breath) ...trading and tributing favor could end up with odd balance problems, so I doubt it'd happen. That is, of course, entirely speculative.
And you'll note I used the word 'difference' three times in the one sentence.
TheShædøwDåwn
If you're like me, then it's possible you're a clone generated from my stolen DNA. I suggest you turn yourself in for destruction immediately.