I've been thinking about my own build plans and how I'm going to run the bed. I'm considering the skate method as it's simple and cheap. I then thought about using v-groove bearings and running them directly on top of a piece of angle. My sketch-up skills aren't great but hopefully you get the idea. It would be a moving bed with the top bearings attached to the gantry. It's only an idea I had today so they may be obviously floors that I'd not considered yet but it may be worth experimenting with?