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1 - Very interesting. This is something I've heard somewhat hushed whispers about on old forums. People would say "I could get you 4cm after growth plate closure, $2k usd is synthesis price, good luck getting cheaper." It also appears like there have been studies on BPM's that have shown that they can cause growth. I'll really read into all of them after my lectures, but it does seem somewhat interesting.
http://www.naturalheightgrowth.com/2013/05/27/increase-height-and-grow-taller-using-bone-morphogenetic-proteins-bmps-part-ii/Right now my rudimentary prediction is that if the formula you linked works, it may be re-inforcing cartilage tissue that exists at the end of the bone, causing it to become thicker and mimic the effect of bone growth. Perhaps like glucosamine but on steroids. I could see how something like this could provide maybe 3-4cm after growth plate closure.
2 - Yes messing with all these things will undoubtedly cut your life span. Taking HGH for a long period of time (like children treated with it throughout adolescence) had like a 7x higher stroke risk (although this study was discredited by the FDA, my hunch is that big pharma had a hand in that). The reason is this: HGH causes all of your cells to replicate, not just your bones. This is why you see people saying HGH helps skin, hair growth, nail growth, etc...
The problem is this growth ALSO includes all of your internal organs lol. If your growth plates are fused and you take too much HGH you will die because your skeleton will no longer be able
to contain your organs. But even before reaching that point, as you make your heart larger, your lifespan goes down significantly. Not only just from risks like "tall people may get more heart disease and cancer" just by default of having more cells, but also because your body is lopsided. Your brain may be too big in x part for blood to properly flow into y part, your heart may be producing too much blood for h part to work properly. There is a perfect, natural balance to the human body and taking HGH will fk up this balance and reduce the efficiency with which the overall body works, leading to an earlier death than usual.
But note that these kinds of effects would only happen after taking significant amounts of HGH. I mean you'd have to be on for at least a year before really anything happens. (Unless you're doing something crazy like 30iU a day).