Six to eight IU's/day is a lot. At that level I wouldn't expect sides like organ growth, acromealgy, etc., but I think you would certainly experience a lot of edema and joint pain, and the potential for carpal tunnel syndrome. It certainly could affect dormant cells, which is why it's smart to consult with a doctor regarding your personal and family history of such diseases before starting GH or AAS.
The biggest downside to GH, IMO, is the cost. You'll likely spend a few thousand dollars to run a cycle of it for any appreciable length of time (especially @ 6-8 IU's/day). According to some, it's also one of the most overrated drugs ever, in terms of cost vs. benefit. This (IMO) is really something to consider, because for the cost of GH you can run a ton of other AAS drugs and get extremely good results.
