Wow interesting videos.
I don't think such musicians at that touring level will ever use an arranger
I have to travel far from home tomorrow for a gig with a band (not arranger).
I have just received my Korg MicroKey 61 2 Air, and will use it. It is so lightweight and I start to accommodate with the small keys.

vArranger as a sound module / setup-sound changer, mp3 player, vst host is also very good.

I want now to create a little box to put all the gears together

By the way the microkey air does not work wery well with bluetooth midi. If you go a bit far from the commputer, you have not pleasant latency. So it will not be useful I think... maybe with the mac or ipad it will handle it better than windows?