Actually, you would be better off to use both in the same cycle, because they work in synergy to cause lean muscle growth and a change in body composition. Seperately, our feedback mechanisms tend to interfere with desired results. GH alone causes a downregulation of the natural production of insulin-like growth factors, and IGF alone inhibits natural production of GH.
Perhaps the most relevant effect of IGF-1 to this discussion is the ability of IGF-1 to increase protein synthesis by increasing cellular mRNA formation (mRNA makes protein) as well as increasing uptake of amino acids. This effect on protein synthesis can lead to increased lean mass. The research indicates that this effect is dependent on GH presence as well. So IGF-1 alone does not promote such effects. Nor does GH. It appears the combination of the two most consistently lead to increased protein synthesis.
GH and IGF-1 are negative regulators of GH release so an increase in either (from a GH injection) reduces the secretion of GH.
The leading studies in this area: (Ney, 1999, Yarasheski, 1994....Am J. App. Phys.)
And yes, I have personal experience with both.....years with GH, IGF-1 is very difficult to obtain in a useable condition....it must be handled very gently and have bee kept at a rather precise temperature at all times. I am familiar with your source, and am very hopeful that this turns out to be the real deal.