I posted on a few other pages but thought I'd add to this one for anyone's future reference.
I did some chrono testing with my 3 PB's using the same arrow, a 478g Outlaw. I realize the one is a 45# and the other 2 are 50# but it is what it is. If I get a chance, I'll try and go back and redo the 45# to equal the gpp of the others.
The PB 100 50# shot 173.4fps @ 31.92fpe at 9.56gpp and 64% efficiency.
The PB 300 45# shot 165.4fps @ 28.94fpe at 10.62gpp and 64% efficiency.
The PB 600 50# shot 170.6fps @ 30.90fpe at 9.56gpp and 62% efficiency.
Efficiency is FPE / draw weight. I'll try and get a 9.5gpp arrow with the 45# so they're more indicative of each other.