I have also noticed something interesting about the Ardex 8+9. It seems to gas or create little pockets of air when curing. I have done a number of test boxes to first test that it holds water (never had one leak) and then how strong they are (the product is really strong - much more so than liquid membranes). In doing these tests and looking at cross sections of the dried product I see these little bubbles trapped inside the product.
I have never seen this anywhere outside of an Aero Chocalate bar.
Take a look at this swatch I tested in the cold.
This is Kerdi DS with a patch. I cut a hole to test how the product does in cold overnight lows (3 C).
Patch added over top with Ardex 8+9 only.
Left patch overnight in my truck and the next morning tried to pull it off. It came off with no effort and you can see all these tiny air bubbles. In the center you can see where the product dried (darker colour).
I pulled on the left edge and pulled the fleece right of the Kerdi. Nice bond strength there!