This has been mentioned before. +1
The capability of adding individual midi parts to RB projects is amazing... but the inabilty to preview the parts makes the feature inconvenient to use effectively.

ability to preview midi from styles would be a MAJOR enhancement to RB... people would get a lot of use out of it. Especially given the sheer number of midi styles , it would unlock literally thousands of new creative opportunities... and it would make RB more user friendly to the MIDI only user base.