I have an A25, but I just use it mainly for Mono lines and controlling the Komplete Kontrol software, along with recording CC#'s (the A25 doesn't have 5 pin din, by the way).
Also, I use it for Drum and Percussion programming/parts - I just use the transpose buttons if I need more notes.
My main controller is a Studiologic 88 (one of the older models - about 16 years old and I love it for Piano playing. It feels nice to play).
That is a 5 pin din. I don't know why, but I feel more comfortable with 5 pin...maybe I'm just too old school still in my midi thinking.
Yes, you are right, for some reason, three octave controllers are few and far between these days.