The comp on it to me seems really transparent unless you get heavy handed. I think with the SSL comp it imparts more character at more modest settings. IMO in a QUICK test on a song that had Ozone 4 on it, the transients can definitely be made sharper with a LOT of volume through FGX. I can't really do much loud monitoring now, but the transients can really be brought out. In a static mix like I tested, it was almost like the snare popped OUT more just using FGX. I can't really test what I think I hear at an acceptable level, but if it sounds like I think it does at modest to loud volume with as low as I was just listening, it would take out my 2 instances of GClip and my 2 instances of Ozone (I use one in the middle of my mastering chain for saturation, light limiting and EQ if needed, and then another at the end for final limiting and dither).
It uses a lot more of my CPU processing power than I had hoped, though. It takes as much CPU as my 2 instances of Ozone and 2 GClip instances combined.