The champions have been balanced by reducing their troop capacity - otherwise they'd be much too powerful. Just because a general isn't as powerful as you'd like dowsn't mean it's unbalanced. I think they are all about right, if you assume that each general was designed with a specific type of target in mind. The Scientist may appear largely useless, but he comes into his own against high-level opponents. The fact that he's not very useful for lower level players doesn't mean he's unbalanced, any more than Drac is unbalanced, even though he's pretty much useless when you get into the Arabian adventures.