I first tried the Gewa Bio and the Gewa Air Oblong. But this shaped version of the Air 1.7 model is by far the best: super light yet sturdy. You almost forget wearing it!
(+) A Bon Musica shoulder rest fits, but you have to leave the storage pouch out. The handle doesn't rattle as loudly while walking as with the Bio model, only occasionally when you bend over. I chose the matte black version for the least risk of scratches. It doesn't have an attached sheet pouch, but even the sheet pouch of the Air 2.1 didn't seem large enough, and I would end up bringing an extra shoulder bag anyway. The most important thing for me was as little weight on the back as possible!
(-) Only the shoulder straps sometimes get in the way of each other when putting them on, but that's really minor.