I'm happy to hear GS is doing this. I've passed up some rare games that I don't see often because they lacked manuals or art (usually both).
I'd go for Haunting grounds - been wanting to try it out.
The manual states you need a 360 controller for each USB mic you plan to use (unless you have one of the mics with controls built into it). So if you have 2 controllers and 3 mics, guess what?