I understand that alot of people like to just have a box with worms in it. However, when it comes time to harvest the vermicaste Amy's style of worm box creates a lot of work.
An hour and a half! It takes a few minutes to harvest a tray from a Can-O-Worms. This method of vermiposting is just too labour intensive for me. I think I would stop feeding them from dread of having to do this job. I have 3 Can-O-Worms bins and 2 Worm-A-Roo bins. Any one of these bins can be harvested in a few minutes. If you go to harvest your Can-O-Worms and find that the worms are still in the tray you want to harvest it is easy to just do it another day. They might be in a lower tray because they felt a bit hot or because they knew it wouldn't rain that day so they are off for a bit of exploration... who knows. Chances are that they will not be in the lower trays for long.
Another problem I find with the idea of manually seperating worms from their castings is that any tumbler as shown on Amy's site must allow some of the worm eggs and new born worms through. This is a whole generation of worms that are being thrown out into the garden where they are unlikely to survive or don't fit into the eco-system.
I have stopped throwing away all organic waste. I only put my bins out once every 6 weeks or so unless they get smelly. This is compared to every week like my neighbours. To put that much rubbish through worm farms that have to be sorted manually would mean that I would be spending hours every week emptying worm farms. It is most important to know yourself and I know that I would get sick of doing that very quickly.
So, my advise, for what it is worth, is to spend a little extra so that you can fully enjoy your hobby and get the maximise the environmental benefits.