Thanks for your comments. A few of our customers have contacted us about a tight fit in the AeroPress, so we made a fitting guide to help customers in this situation. Perhaps the guide will be helpful for you: http://kaffeologie.com/s-filter-fitting-g
As you noted, because the S Filter is slightly thicker than paper, the AeroPress latch will not close to the same degree. As long as the latch interlocks with the slots on the AeroPress tube, though, the lid will hold securely.
With regards to your second issue, the S Filter is made of non-absorbent metal so it does interact with water differently than paper. That said, it's possible to brew a good cup of coffee with a few simple technique adjustments.
We've made a couple of brewing guides to help our customers with adjusting to the S Filter. These are listed on our packaging as well. Here's the link:
If you haven't yet, please give these guides a try and let us know what you think (write firstname.lastname@example.org).