The enlarged sig is something like what Lucifus has. He won it in the deadfire sig contest a while ago. I'm not sure if you were around then, but it does not seem to be a problem for him even now.

Rep boost is absurd. It defeats the system entirely, and is probably an option only rep failures would choose.

Animated avatars is a great idea if its possible.

I think the username changes are already being used to identify mods and admins. I would not want a colored one though, since it seems like the user is begging for attention.