I was curious if there has been any further discussion of tearing down the MagicBand. Apparently Disney is in the middle of a test. The current round will have 80,000 guests using the technology during the month of August. That is a lot of people, but nothing like the 120,000 a day that will be using it when the system goes live. That is a lot of tech walking around on peoples wrists. I should add. When guests go home after their trip to "The World" they will be able to keep their MagicBand. It would be awesome if other uses for the device could be found outside of Orlando.
Here is a link to the FCC filing. When you read the various papers submitted for peer review by various Disney research organizations (including Imagineering), it becomes pretty clear that Disney's plan is to utilize the bands to track each and every guest in real time, and offer various incentives on the fly (bonus fastpasses, reservations for tables, etc.), to distribute crowds throughout the park more efficiently. Think air traffic control for people.