I have definitely considered doing a metheglin with something from Teavana...I don't routinely add tannins to my mead except in certain circumstances, but it can be a valuable addition at times. I would think that many of the Teavana teas would have less tannins than your run-of-the-mill black tea (many of the Teavana teas I've tried use white or green tea as the base...)
Packaged: American Pale Pacific Gem SMaSH
Recent Meads: Mead Day '11 Ginger Metheglin, Mead Day '12 Traditional (orange blossom) Mead, Simple Cyser '12
Primary: Red X Weimea SMaSH
Secondary: Why do I keep this line here...?
Bulk Aging: Cocobochet, Wild Cider, Simple Cyser
Planned: Hop Metheglin #3 (NZ hops), Trad. Gesho T'ej