I personally don't like the current banner; the old one was probably the right level.
I just think that the wikipedia needs to get itself to the point where the interest on the money it has is enough to run the servers forever, and any excess per year can be given to charity.
Right now, of course the traffic is climbing, but probably you could estimate what the maximum traffic it could get would be if everyone used it. Also the cost per click presumably is going down over time, so you would have to allow for that as well.
Anyway all that may well mean that they need to put the old banner back and leave it there for a few years; the current one is too intrusive. IMO