The key to this simplest approach is the throttle set-up. I have thumb inside of a left-side, half-twist;I like the elegant simplicity of your 2wd approach/philosophy.
It's very natural and intuitive. Although, most of the time, I'm running the rear(main)motor w/ the PAS, so I'm only using the thumb on occassion to activate the frt. motor.
Most hub motors on the street are best served by using a "middle-of-the-road" mid-speed range, I my case both are 260RPM @ 36 Volts. Running a single motor on 46V LiPoly, top speed is around 22 mph and it will climb most hills, although some slowly and needing all the help my legs can provide. Running both motors, top speed increases to 25-26MPH and any hill can be climbed w/out slowing down much at all. So the performance envelope has been "widened"(something a mid-drive will do over a single hub). So my performance goals are met, while retaining the simplisity and low maintenance of a hub motor.I would like your rig as a mid drive also (maybe a 2 speed xiongda on front - bit heavy tho), with a focus on relieving stress on the chain transmission for torquey starts and hills (favouring the low gear of the XD).
If one is using "plug and play" style packs, plugging in 2 is hardly complicating anything.
I do like KISS tho. Get home, park bike, connect 1 charger to 1 big battery, relax. Anything too fiddly is a dis-incentive to using the bike over the car. simplicity is part ofthe bikes appeal.
My main pack is too large to remove, but my smaller "aux" is easily swapped and i have 2 of those;
I can see merit in 2 identical batteries tho. One precharged spare third battery can be swapped to either motor.
20Ah pack in the frame bag, 5Ah pack is in tube under frame down-tube.