I think a german subform on talk.maemo.org would be great. Localization works for a lot of sites...why not here? I don't believe that it will be a problem to find mods.
Using another site than the official maemo page is suboptimal. Having everything useful on a single domain is a huge pro imho.

Altough my technical knowledge about the N800 is...lets say improvable, I have some basic knowledge and could help fighting spam and other garbage in the forum. Actually my english is a bit rusty and not as fluently as it was years ago but I could also do some translation.