Ironically, I recently bought a used M12S while I was waiting for a replacement steering drop down to arrive. After 3 years of use, the Graupner started to glitch on the steering because the potentiometer went bad, very common regardless of the brand of radio you buy. For $40 I got a whole new drop down assembly shipped to me making it a super easy repair. In the mean time, I struggled to learn how to use the M12S for a couple weeks, the menu navigation was clunky and way more difficult to use the jog wheel which is a design flaw in itself, they tend to stick and need to be replaced which increases frustration. As far as feel and performance goes, the M12S was every bit as good as my Graupner, only complaint I have is the jog wheel and couldn't wait to go back to my Graupner. I'll keep the M12S as a backup, it is a very nice system, but definitely has its flaws.

So how easy is it to replace the steering potentiometer on the NB4 when that time comes?

Also worth clarifying that the older Graupner X-8N radios had some firmware issues, they have since worked out all the kinks with the latest firmware with the X-8E which offers tons of high end features for a mid grade price point, that's the point I was trying to make when someone was trying to compare Sanwa to FlySky... I feel that Graupner is perfectly matched between those two options when combining features with price