I don't agree fully, the Starfleet photon torpedo in TNG series was type 5 i belive, while in FC it was type 6. I read through Mike Wongs website were he said the Federation fleet overwelmed Borg defences with sheer firepower.
Im usully wondering how did Starfleet manage to inflict damages to the Borg cube in First Contact when phasers and photon torpedoes didn't make a scratch to the cube at the battle of Wolf 359.