Smallblock Pistons: 1 question.....KB's -or- Sealed Power(SpeedPro hypers)???

The brand is not as important as the type of piston you choose. Hypereutectic pistons are still cast pistons, and they will not tolerate the abuse that a forged piston will. They do run quieter at start up, and they have good wear characteristics, but if you plan on a high rpm motor, any sort of power adder, or if there is even a chance of detonation, I would use forged pistons.
If the motor is basically a daily driver with just the occasional romp, you may be fine with the hypereutectics. Many OEM high performance motors come from the factory with hypereutectic pistons, and they are generally reliable until boost or nitrous is added. It should be noted however, that these modern high performance engines have computer controlled anti-knock systems to prevent accidental detonation, which break hypereutectic pistons really quick.