Jesus Christ you guys went HAM on this topic. I couldn't read through all of it but I just wanted to add a point.
Gohan is considered Goku's superior without a doubt, he thought Goku wasn't even going all out. Cell's punches damaged Gohan a whole lot, I don't think that would be possible if the power difference between Gohan and Goku was significant. I think Gohan would be able to handle the shots Goku took easier. Just because someone is increasing speed, doesn't mean power isn't getting increased as well.
I think the only other variation is that Gohan is heavily speed weighted, which is possible too. AT always puts around the issue when Goku gets surpassed, so he could be trying to not make it seem that way.