For pro BB, who knows what doses of HGH they are using, and how many AAS at what doses, along with other drugs for all sorts of things...I think it would be really hard for pro BB who are on so many different types of gear, to pinpoint what is exactly doing what. Too many variables. But I am sure many people have selectively done their own experiments with compounds to see what works for them at what doses. There is individual variability to all of these things, even food, supplements, etc for each of us as to what will work so so, good, great, amazing or not at all. And I have no clue on some forums that claim to tell what pro BB use, but if they are indeed accurate heck I have read that supposedly guys do 10-15iu of GH a day, IM or IV, multiple dosings per day, etc. My gosh if you can do 10iu a day of legit HGH, and drop it straight in a vein, I am guessing over time you might see some sick results, but is that realistic for you and your budget? and once you push GH to the extreme dosing limits, or some AAS, what is the trade off in the health risks those doses might present?
GH does some marvelous things, but if its just muscle size you are looking for I do not think its the magic cure. Healing up injuries and connective tissue, I think that is the real beauty of GH. And over very long periods of time dropping bodyfat IF you are already pretty lean.
I do not think GH separates the gym goer from the bodybuilder. There are probably more wealthy old ladies and middle aged men enjoying GH than BBs, and not to get jacked either just all the other benefits. I am not a BB, always trained like a PL/OL, so I can not give personal experience, but friends and others I know who are BB that look legit and are definitely not going to be mistaken for the average gym goer, have one or more of : genetics, crazy work ethic, smart training methods, consistency over the long haul in the iron game (they have been hitting the gym for YEARS), impressive self-discipline with eating clean, smart supplementation, and for some yes juice.