batteries generally also bleed some charge will charging. if you cycle a battery a few times on a charger that has a discharge function you should see that it almost always chargers more mAh into the battery then what comes out of them. lipos are way better about this than nickel based batteries but still do it. dont ask me where those extra electrons go though

but on the original point. a good balancer should get the cells to be within one hundredth of a volt (.01) of each other. the biggest concern is that no cell goes beyond its voltage range (about 3-4.2v). so when your speed control hits LVC, for the first few runs double check the individual cells with a digital voltmeter and make sure non of them are below 3.0v per cell (worst allowable scenario is if one is under 3.0v but gradually rising to above 3.0v in a matter of seconds). the charger, if its doing its job, should have a safety to keep any cell from going over voltage. unfortunately the VXL speed control does not have adjustable voltage cutoff so as the pack ages you may want to eventually make sure to stop running before you hit the LVC just to protect any weaker cells.