I think dual-class cards sounds much cooler than it is in practice. You only play one class at a time anyway, so it really is just the same as a neutral card you can play on two classes instead of 10. Doesn't have strategic impact the same way MtG bicolor cards have.
I like it because they're keeping the same amount of class cards overall but each class gets 4 extra class cards to play around with. Since the cards aren't neutral you can be a bit more liberal with the power level of them.
