I think the earth earters will not mind, but I worry about the discus
Now my knowledge of discus is fragmentary (to put it mildly
) but as far as I know, discus eat slowly, and likes to feed from the bottom.
Gophagus eat very hungrily, the like to eat from the bottom, but don't mind coming to the surface too much. So I think the discus would starve
Further, discus are supposed to be stressy, while at least some Geophagus are very active swimmers
However, thinking within Geophaginae, I think of Biotodoma - which are peacefull (many reports, at least in my language, Dutch state differently, but these are wrong), quiet and slow eating.
I never kept Guianacara, but would advise against Satanoperca: the unspotted ones are still too active, the spotted ones may be agresive (daemon especially)
Keep some 6 of them in your tank, and these might combine with discus. At least they will fit much better