I would have agreed with Steve regarding the JG6 bands until I read Mols article, but now that I have I think he's got a good case with proof not only in CEARs but at least one photo.
I don't believe the Fels am Wagram machines to be JG6 anyway so for this case it's of no consequence. I'd say aircraft from III or IV JG300 is possible as they had darker blue than I and II gruppe.
As an outside possibility, when II./JG51 ended up at Wagram maybe they did paint up their aircraft with Green-white-Green after all? There's no photographs that proves the contrary anyway. It's different with JG52 as there's good photographic evidence that they did not use the bands.
It would be quite risky to say the least, for someone to say "let's skip those I.d. markings, we're about to lose anyway"
/Anders