i have used GSA SER+CB for 2+ months. here is my experience. i create tier-1 articles, and social network. then blog comments, trackback, shortened url as tier 2. i got NOTHING. one of my sites experienced some serp drops. some people told me for youtube, i can just spam the hell of it. but i got absolutely no effects. (in fact, i saw some high-ranking youtube videos have nothing but 300 or so social signals. i bought signals from fiverr, and i got nothing too.) the gsa seller was diligent in helping me, but never really solved my problems. 1, LPM in single digits, even though it was like 500 on his machine. (my vps does not appear slow.) 2, Do-follow percentage is very low, around 50%. 3, constantly running out of places to post links!