It appears as though this might be available from factory now - I received my first S1 yesterday and during brief testing appeared to load balance between 2 pools without me updating anything.
Once I receive the powersupply I am going to run the S1 with (750w dell with breakout board from gekkoscience), I will test further (I didnt try percentage hashing as I didnt quite realise what was going on) and report back here.
I'll be interested in what you find out. The one I have on the OP is a specific method of multi-pool strategy called load-balance with quota (using the flag -U equal to the flag --quota). It was changed from flag -o equal to --url
You can see the explanation from the github of the developer of cgminer Con Kolivas
https://github.com/ckolivas/cgminer