So this is my first post here (as you can see), I currently have 6 polys all upper jaws with a threadfin acara and a Topajo both are geos. No issues with the polys and geos except the Topajo pushes the polys out of his area and the thread fin too for that matter. Never any damage. The Topajo will allow the golddust in his lair but only the golddust. One time my albino sen grabbed the threadfin by a fin during feeding time but it was a mistake and no real damage done. Id go with the geos over the Sevs. Ive had Severum and they can get "picky" I did have my Sev in with ropefish and a sen. That was 20+ years ago. The Winermilleri get along in a group together and look sweet doing it. Originally I was going for an African river biotope, but had a hard time finding pretty not super huge fish to go with my polys. So the two geos fit that bill. Just my 2cents, was waiting for the right moment to come up for air.