I disagree with access. I think Igf1 is worth it for muscle growth as well. While access has stated numerous times that he hasn't had any success with igf for this I certainly have.
It might not bring fantastic gains but it can do something even better: It can make site injections work! I have had visible success with using igf to bring up lagging parts.
You already know the idea of causing hyperplasia in the muscle just worked no doubt. While i've seen no hard scientific evidence backing the theory behind this i can vouch for it myself. I do think it is the same thing as with hgh tho: There are great individual differences in how effective it is.