Gamescon is actually called Gamescom - assuming you mean the trade fair in Cologne. It is typically more for gamers than developers, but it has a huge business area (which you can enter if you are an exhibitor, trade visitor or press). If have appointments in the business area or even your own booth (or form a group with other indies to afford a booth), it is certainly a positive and enriching experience.
So far I've only been at gamescom as press, but if I remember correctly there has a been an indie booth in the business area a few years ago and this year a few smaller german companies had their own shared booth. (Some went for some smaller mexican companies as well as some nordic companies)
You forgot Devmania
in your list, a german-speaking-only meet-up/jam-type thing.