I bought one as well a couple of weeks ago.
I do not really need it at the moment, but since my festool stuff tends to stick around and I see myself becoming a house owner during the next years, I wanted to have a "future proof" vac that would also be able to handle drywall sanding, so went for the CTM E AC.
You have the big knob for man/auto ON/OFF, the suction-regulation, the "hose-diameter" selector and the auto clean-regulation.
As far as I can tell, the hose-diameter selector also just seems to set the value for the sensor, not impacting suction.
So far I like it a lot compared to my previous old Karcher unit, which was more like a hamster with a respiratory problem.
I also have the CTL-SYS, which is brilliant for "on-site" work or the quick job at the relatives, but needs the bag to be changed just way too often, because of its size...