I think pet power hour may mean more gains for the first hour not a higher percentage per gain. I do notice more gains total in power hour when fighting. This observation is based of training 4 lvl 4 pets while rotating them out when they cap at 25% on the crazed mage for a few hours.
I guess someone would have to measure the gains "in total" within that hour... with outside the hour. Same spawn, same amount of kills. Constant as possible.
I always thought, with classic Power Hour... you got MORE gains, per the hour. At least back in the day, you were wasting resources to run a crafter outside PH. Unlike combat, where it was more about having fun.
Maybe its like the modern TV definition of "New" vs. old "New". In days of old... "new" means the whole show is brand new. Today, the show can be made up of other shows and called new. Some, little, to no footage could be new, yet its still "new". hehe