nah.. ure giving Colossus too much credit. she is definitely stronger. i say she's around Wonderman going by feats and who she has gone toe to toe with. Colossus may hang with Gladz a panel or two, but then it's usually established who is far and away superior.
She fought WW in a pretty long sparing fight where she did fairly well but lost, beat WW One Million (who's less experienced than modern WW), has beaten Supergirl iirc, KOed Superman once (he wasn't really fighting back but it only took two hits to the face so still major power feat for the rod), and has a mixed record against Lobo, she's done both well and poorly against him.
When has she done well against Lobo? I only know of the instance Tyrant named. One more thing: by saying that she 'did well' against Lobo, do you mean that she only held her own or defeated him?
Three meetings. One she was disguised as a Czarian and was in a long bar brawl with no victor between them. One he tried to get the drop on her and she just boom-tubed him away. One he got the drop on her.