@billyb Here are the comparison pics for PowerBow 5 and 6. There are some differences between these two models.
Handle => PB5 oval handle is more pronounced and its perpendicular to the blade. PB6 oval handle is parallel to the blade where it almost feels like a flat/square fit to the handle. I hope I am making sense here
Back Profile => PB5 features a full profile but PB6 is slightly bordering on a convex profile.
Face => PB5 features a full flat face, but PB6 has a slight curvature. I don't think its a like GM F4.5 but I would put it somewhere between F2 and F4.5. You can certainly notice the curved face when you see the bat in person.
Hope this helps ...