As far as the Justice, 4 FPS is the best case scenario from individual bow to individual bow. I would say 6-8 FPS would be a more realistic number.
Jeff, why do you think this? I was basing my 4 fps estimation on the difference in the IBO ranges... Justice at 296-304, Liberty at 300-308...
Now if there were some reason the Justices would tend to run and average more towards the low side and the Liberties towards the high side, I would agree with your assesment, but there isn't any technical reason this should be so, is there?