I was reading your review.
Perfect, well done!!!
Yes you are right, the 12 is cheaper at AMAZON.de
and has the exactly the same functions of the 11S .
There is one trick I have to tell you:
You might tape 2 small little stripes of foam-tape at the "bumpers"
above and under the front sensor.
This is protecting the robot and your furniture perfectly.
There is no need but I am always a little bit careful.
If you have more questions about the robot, don't hesitate and ask.
The friends here and even I have some experience meanwhile!