I think that the fact that "text-heavy banners get high click-throughs" is pretty counter-intuitive.
Also, have you tried using CPM rather CPC?
Also, have you tried using CPM rather CPC?
Stuff that is mainly graphics is easy to just mentally filter out with the rest of the website chrome.
Just a guess, but the less "bannery" the ad is, probably the better chance it has of being noticed. Ironic, since banners got so obnoxious in the first place as an attention-grabbing mechanism.
What do you mean by the latter question?