They are around the same because both have heavy UP requirements. Gellius for the dps that need to help him kill things and Nadia for the UP she needs. In both cases you won't be deploying them early but they are both broken units in their given roles. That doesn't mean the other is better and i guess the others are pissed off at you because you stated Gellius is better everywhere.

In most cases you will deploy a soldier or two, then something else and if nothing else is needed for the moment you will just wait and store UP for when it is needed. This is where Nadia can replace Gellius for most maps. If you need a heavy armour down fast for some reason then of course he will be better. But i barely see any maps where you need one down asap so you can just wait for Nadia to get ready instead.

That being said, that jungle subjugation map on DMM is like made for Nadia, where can i get my free copy? >.<