I've heard Dan Quillian say that increasing your draw length by 1" was like increasing draw weight by 10#......... He was prone to exaggerate to make a point.
Nothing but respect for Mr. Dan, but I agree...that was a bit of an exaggeration (and I'm pretty sure he assumed we knew better), plus Mr. Dan was actually an experienced hunter. The one I referenced before tries to pass it off as the gospel truth and has only killed time.
Power stroke does make some difference, but how much? I do know that if I were gaining that much of a performance increase (supposedly shooting like a 70# bow) there's no way a 32 inch, 500 spine carbon arrow with 200 grain points would fly anywhere close to straight. B.S. doesn't trump physics.
I normally shoot arrows that are 8-9 gpp at my actual draw weight. That's going to put me at around 6 gpp (using his formula), which I'd think would be blowing up bows...especially self bows...but on the flip side, until it blows up I should be getting well over 200 fps....and noisy, shocky bows. Doesn't happen.
It's not that hard to figure it out. Use a little logic, a little common sense, a little EXPERIENCE, and you can easily determine what's fact and what's imaginary book filler.