Hello Christian,
I have a Montane Aero Smock which is Pertex Quantum like the Ion. I just purchased a Large Montbell Stretch Wind Jacket. Because it just arrived, I haven’t had a chance to use it yet. I thought it might have advantages for aerobic winter activities and that is why I decided to try it. It doesn’t stretch as much as, e.g., capilene base layers, and although I normally wear a large, it would be interesting to try it in a medium size.
My Montane is a favorite piece of clothing but the sleeves are on the short side. My Montane is an X-Large (I bought a size up from normal because of comments about Montane being small). The Montbell has sleeves that are a much better length for me.
The measured weight for the large Montbell is 169g. The measured weight for the X-Large Montane Aero is 92g.
I’ll try to remember to report back after I’ve had more experience with the Montbell.
Craig