Here are my 2 cents on this thread
I would try and get those Programs which convert for each country the best. Try it regional
meaning, start serving your audience banners and sites they will understand.
You mentioned you also have some European traffic on the site.
Try to break that one up and promote different things in different countries. If you need a re-direct script, we recently build a generic one for our webmasters to use, so they can start targeting by country even better.
Hit me up for more details and of course if you want to start sending some German test traffic, I'm sure we can convert that for you