Conclusion: I've yet to be convinced that these ships had any badges other than the crowns. There is no hard evidence to be found in the www other than unfounded claims. Concering the crowns, only König and Großer Kurfürst have theirs documented by photographs. If one wants absolute certainty, Kronprinz and Markgraf should be depicted without any crests, and the other two only with the crowns; the crowns for Kronprinz and Markgraf can be retained if an educated guess is enough. As for KimWerner's badges (sorry, no insult intended, really) I don't think we can be certain enough about their authenticity to use them.
I'm agreeing that it is very hard to find hard evidence in the net. I don't know how official this site (
www.deutsche-schutzgebiete.de) is, but it seems very accurate regarding historical facts. It's through this site I try to confirm info's and I will claim, that historical postcards combined with other (old) sources gives a certain certainty though