I guess I just haven't seen any need for movement in WotLK encounters with the exception of the new ICC heroics but even then they weren't much issue. In fact I can't think of too much in this game that requires movement. It sounds to me like your mage DPS problem might be from just wanting to be mobile for the sake of being mobile or just lack of something.
Anyways as for the topic team I would still recommend a tank other than warrior but theres no reason why you wouldn't be able to clear anything just fine with it.
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