Is the Gridseed controller required to run these units or can I run 10 of them from a PC using USB hubs?
You can connect these to a windows PC and run the custom version of cpuminer so no you don't need the controller, but for the extra $ it's worth it considering how many watts a PC uses...that and you'd have to run like 10-MS DOS windows of cpuminer which is just a clutter on your desktop if you're actually also using the computer for non-mining stuff.
My understanding, too, is that if you mine with your PC using the custom cpuminer, the bitcoin cores will stay active and draw power...so if you only want to mine Scrypt coins with them, you'll be paying more in power to run them that way.