I migrated from OE to TB some years ago. I never regret it. However, I am not using stationaries.
The following links might give you more information:
How to migrate from OE to TB:
http://blogs.techrepublic.com.com/howdoi/?p=125
http://kb.mozillazine.org/Thunderbir...utlook_Express
TB Stationary Add-On:
https://addons.mozilla.org/en-US/thunderbird/addon/4394