I'm probably going to get a Shiftster soon. I have owned this truck for 14 years now and, lets just say the electronic shift motor mechanism is not very reliable even when cleaned and maintained.
I'm not as flexible as I was 10 years ago, but I can still get under my truck.
My theory on the Shiftster operation with manual hubs is, if I don't want to get under my truck, at that particular moment (lets say its snowy or wet under there), I can just get out and unlock my hubs, while the t-case is still in 4H, and that would work for a short time until I got into my cozy garage to get underneath. Sound ok?
All that would spin would be the front driveline, but, I don't see that adversely affecting the truck with the hubs unlocked.