Can we actually playing the origins even pick a different class for the 'non-Urge'? Would be odd if you couldn't, but then in the game you go and respec yourself and your companion's base class.
I guess it depends on the character's story. Astarion could be a lot of things... Gale? The Waterdeep wizard having an affair with Mystra? It takes some creativity to turn him into something else - but the main issue is that the game's story probably ain't doing much to support the change and rather just cuts dialog options/reactions.
