I've got an SC8 and am a huge fan. Depending on how you look at it, the first vehicles out usually define the class. Therefore, I do believe that if a "spec" situation does arise, it will be with a truggy length chassis.
In watching the differences, I believe the tires are the number one distinguishing factor for what defines a 1/8 CORR truck. If you allow a buggy type tire, then it is, as stated, a buggy with a truck body. So if the vehicle doesn't have the SC type tires, it's not even worth the effort.
For the motor, I have mixed feelings. I do like the fact of having specific motor requirements, and there are pro's and cons for .21 size, along with the larger size. Making these trucks faster with the CORR spec tires I think can actually be a detriment rather than a benefit.
Either way, I'm looking forward to 1/8 SC truck racing to grow and grow.