Well i only own and use the original model, without the arm function for beam scales, but when you use the light shield they are really identical so.
The only negative thing about it is that it takes a long time to start trickling if it is adjusted for a slow feed, have not used Retumbo in it since the supplies of Retumbo here is scaringly low i use powders i have available, it does work fine with H1000 and N570 witch both are quite large in kernel size.
Having the hopper filled up will help with the flow, adjusting the nozzle weight to fast every time you fill it up helps some, and also rotating the base.
The feed of it is based on the vibration motor as it is what fills the tube and distributes the powder, so as long as it vibrates it is filling the tube if not there is something off about it, or an obstruction at the end of the tube.
Never had any issues with that except for that it takes time to get it to feed the powder out of the tube.
If it is giving you trouble i'd send a mail or call to the producer, has lifetime warranty and his customer service is quite good.
I do not have the auto version, but it is possible for you to fasten both the scale and the arm to what they stand on while keeping them level, your problem should go away then?
Assume the problem with the arm is that it is simply too light so it is very easy to move.
I use a digital balance with mine, and put the nozzle under the draftshield and over the pan, and just trickle the loads to the desired weight, have never given me any trouble at all.