I saw that Keyser and Wehrs both have a birdcage that has the caliper mount built into it at the PRI show.

What's the logic behind this? Do you float one side or the other, can you lock the caliper, and what are the effects of using them?

We're still learning quite a bit about spring behind cars, and this looks like another gadget thrown into the mix now. We aren't currently floating the brakes on our current car.