On the other boards PA posts on more frequently, the general concensus is that Formastat/Formasin would be more appropriate for during a cycle of aromatizable PH's, while 6-OXO would be better for post cycle.
I've never tried the Forma--- products myself, so I can't really compare, but I'm on 6-OXO right now for post-cycle, and am very pleased with it. I've kept my weight up, and strength continues to increase.