I found this on the Magellan website. It appears that their Bluetooth is set up differently than the TomTom kit:
Can I undock the iPhone from the Premium Car Kit and keep my Bluetooth® connection?
Yes. After initially connecting your iPhone to the Premium Car Kit, you can easily undock the iPhone without losing your Bluetooth® connection.
That makes sense ... thanks for sharing!
If Magellan handles bluetooth a bit more logical, and Magellan supports all Apple devices (iPhone & iPod Touch) and Magellan can handle covers/skins ... it's worth the $10 more ... too bad they (or Apples approval process) missed the Xmas rush ... TomTom may see some exchanges in early Jan for Magellan.