The 07 STI's did have some issues with their ECU's leading to some engine failures. This is cured by getting a good tune on the vehicle.
The Spec B is a wonderful option for the "family" vehicle. I'm not sure but I think the 06 is when they went to the 6 speed. If they didnt do that till 07 go find yourself a 07 with a 6 speed.
A ton of aftermarket in both cases and really easy to make fun, reliable, streetable horsepower.
Having owned a regular 07 STI I'd gladly take either and would lean towards the Spec. B for the family planning part.