Wow, I'm all for listening to experience, I think it leads the way for science to follow up and start to explain. But neither can be dismissed as worthless, they need to be used side by side.
You've used Mreik as an example in your sig as to why experience beats science but Mreik is probably also the most educated in human biology on this site and his knowledge of androgens is second to none. I think he just chooses to keep quite to avoid being pulled into discussions with internet experts
My girlfriend went on steriods for a blood disorder recently so I asked Mreik about them and straight off the bat he told me everything the doctors already had along with lots of other interesting stuff too on how to stay safe while on them and things to look out for.
He may well have experience of their use (I don't know if he has or not) but his knowledge is underpinned by a vast knowledge of the science behind them and their effects on the body so he would be well placed to be able to take them safely.
I imagine Arnold is also pretty knowledgeable on the subject