I don't think the router CPU would be of any concern because they should be more than capable of forwarding at line rate. And as far as spectrum, you won't be using any extra channels because both SSIDs would be carried on the same channel. That being said, your channel utilization would go up, but again, if it is an N access point your cable connection will saturate long before the WLAN connection does. Quite frankly, the only thing that gets used up is your Internet bandwidth, unless they pull all the caps from a bandwidth perspective and throttle on a per-client basis.

...for our own dynamic system. It is code heavy." Maybe I've been working around software too long, but the more code needed to run a single function generally equates to more software defects. In a balancing and stability control system, I'd hate to be the one to find it.