The Uberstore works well but it isn't perfect. Just recently I've had problems where one box overflows into another. It's quite annoying because resetting the system is tricky.
This chap explains the issue rather well:
He also has a solution, which means taking apart all the workings behind the scenes. I get to reuse most of the bits and I'm going to keep the layout. It's just a bit annoying.
Anyway, that's the next big project. I'll leave a sign by the sorter until it's finished.