hammer4203,
Just to clarify some things to help your understanding...
I have the TB, Bionic, and Xoom.
When I first got the TB, I went from my Incredible to the TB by using the "activate phone" option on the Verizon My Account web site. It did ask for the SIM and IMEI of the TB, then I had to power the phone on and all was good. Verizon's web site saw my phone as the TB.
When I got the Bionic, activation was as easy as... power off both phones, take the SIM out of the TB, put it in the Bionic, and power the Bionic on. After that, VZW's web page automatically recognized my phone as the Bionic now (without my doing anything but moving the SIM). Switching back to the TB is just as easy... and I can switch between the 4G/LTE phones at will, just by powering off and moving the SIM.
The TB or the Bionic will NOT work for anything but emergency calls with the SIM removed. i.e. 1x, evdo, 3G, 4G do not work without SIM.
My Xoom just got back from its 4g update, and I haven't tried using the SIM from my 4G phones in the XOOM yet. But I'd be willing to guess that if the data plan is "compatible" between the phones and xoom, it will work just fine.