I agree, here.
Dual spec would be absolutely awesome, and would only enhance the game.
I think AC changes should be expensive, so folks can't do it trivially, but you should be able to do it. I love that my Knight can dual wield, but I wish he could tank. I would pay a lot of credits to be able to tank -and- DPS, so I'm more versatile for groups.
That's fine. If they are different classes, then give them different class quest lines. Oh, wait.