I am not sure what you are asking with your question on "balance". Are you asking about dish or how the bike handles as you ride? I have many miles on both single fix gear wheels and fix-fix wheels. I cannot tell, either riding or maintenance-wise, the difference. Both have flanges much further apart and more symmetrical than any cassette geared bike so they build up strong, stiff laterally, reliable wheels, even with very light spokes. (The dish in a one-sided track hub is completely trivial.)

Ben