The neoprene case from Elecom is exactly the middle ground, I was looking for. It is very light and flexible and offers two additional pockets of various sizes. The AC adapter and a little mouse fit - the material of the bag adapts. A big advantage when traveling - in addition to the low weight - for me that I can pocket simply "crumple" or roll, if I do not have the netbook in it. Even with power pack in your pocket as that. So the bag, for example, is quickly disappearing in a backpack or a smaller pocket.
At the processing can not be faulted. Zippers and seams have survived the first rough load tests with no sign of weakness.
Addendum:
The bag has mastered several weeks Individual holiday with many flights well without problems. The netbook was always well protected.