If you read "Urban Way", Urban Meyer's spread-option attack is designed to get the ball in the hands of his playmakers and is entirely reconfigurable within the spectrum between spread and option to adapt to Chris Leak, Tim Tebow, or Johnny Brantley. That being said, I would imagine that the spread-option with Brantley will look similar to the Chris Leak version. People do not give Leak credit--he ran the spread-option just fine. He even won a national championship with it. Chris Leak was not necessarily mobile, but he could rush if forced to. Brantley will be similar.
As O-town stated, the offense will be adapted to Brantley's skill set. Unlike, say, the Fun N' Gun, there is plenty of room to adapt to personnel. Fun N' Gun really did not give a lot of leeway to the QB, but it did so for the RB. Meyer's spread-option can run with or without a TE, with a mobile or immobile QB, and a couple styles of RBs. With Addazzio in there battling Loeffler for play calls, there could be a diverse set of plays for whomever is playing offense.