Load balancing is just a waiting connection to all pools in your pool list. Work is then round robin rotation based on pool work quota, meaning each pool simply takes a turn. But there are also other factors in the work quotas, a disconnect will reset the pools quota, and I believe it adjusts quota based on rejects too.

I used to run load balancing between two servers and it was never 50/50, even over a long period. If you want to measure pools correctly, the load balancing isn't going to work. You'll have to setup a separate cgminer instance for each pool, preferably with identical performing card for each pool.