Glad to hear from someone else interested in automatic overdub.
Mike Nelson has heard from me about this "auto-stack" function as well.
I find it really difficult to both remember and to physically hit stack between the loop end presses.
There's so much to juggle on the first loop-- the most critical loop.
Without automatic overdub, the "seam" is more obvious and the pacing is slowed.
I find I lose those audience members that need constant new stimuli. (i.e. most people!)
Honestly I do find it strange that auto overdub is absent on the Rang.
There's even auto overdub on my Strymon Timeline and looping on that is mostly an afterthought.
I've gone through a lot of loopers over the last 10 years. (dl4, jm4, rc-20xl, rc-50, dd-7, timeline, lp-1) but now use Rang III + SideCar as my main looper. (Timeline and DD7 as secondary loopers)
For me, auto-stack is the last piece of the puzzle.