I wouldn't know for sure why Riga switched to Storm and then back, but it's possible he simply preferred the Ebonite equipment and reaction to Storm's. PA switched to Track, didn't match up well enough to stay one of the top ten in the world, and went back to Ebonite/Hammer.
"Oh, these guys could average 250 with a square ball on a house shot" and that's true, but matching up to the right equipment will mean the difference between heading to Tour Trials and coming back to be 6th in points.
SH