Difficult to argue with your thoughts on RB. I would say that even on a "cool" Champaign evening they'd be the favorites IF they can beat JCA, which I see as their most significant threat in the north. I see their toughest opponent in the championship game being Rochester. Maybe not as polished a running system as RB, but this year Rochester has pounded teams with a 250 lb. QB and a 230 lb. running back. And of course, there is the customary Derek Leonard-designed play action pass package to keep defenses guessing.
As far as SHG coming out of the South Bracket is concerned, they are a "finesse" team and are not rugged enough to withstand a punishing running attack from Rochester, much less RB or JCA. The defense appears to be above-average quick, but that is negated if a team like Rochester, RB or JCA simply runs the ball at them rather than around them. Remember that such running attacks are also good at chewing up time, wearing down defenses, and keeping opponents to a minimum of offensive possessions.
Based on the above, I see the Class 4A title gaming being Rochester vs. (JCA or RB).