The PS3 rides faster, lands softer, and is more forgiving than the substance, in my opinion. Basically the PS3 fixed all the things about the substance that I didn't like, while still maintaining a similar overall feel.
I agree with Nick, I ride the Omega (the more friendly substance) and I rode the PS3 Saturday, and I was really happy how the board rides. It rides faster and the pop is just amazing.
just bought the substanes this year and love it! but my buddy has a PS3 that i have ridden a little and i think they are farely close in pop but the PS3 edging seems to be alittle tighter but does land softer. both awesome boards dont think you would be disapointed in either one.