mmm... The new Microsoft Surface Pro 3 is very good for vArranger.
You can change style on the touch screen.
Create your 20 OTS for each song, at home, and change them with touch screen or any midi controller.
I personally still use hardware arranger on usual live gigs, but use vArranger while giging far away and need to take train or airplane.
Last gig, I have used vArranger only to change sounds of my PSR keyborad

This PSR is limited to only Right 1 & Right 2. With vArranger I can play up to 5 layers together, and switch sounds more easily than on PSR

It was fun