….............. here's an example of why more than 10 is useful, since I've seen some discussions here saying that anything beyond that would be ridiculous ..............................
I doubt if you've seen that discussion on these Duet forums - quite the opposite in fact. That's why the designers and developers are already planning for it. I will very shortly have a fully populated Duet plus Duex5 (10 steppers) so can see the need for more in the future.