Yes they are.
If you think about it, the reason CPA doesn't like CL is because CPA needs to CONVERT the users that you refer to their website. Your leads have to be quality in order for them to profit!
However, Clickbank is just a one time payment to purchase the product. The only downside is that it is not as easy as CPA to convert, but you should be able to get a decent profit doing that if you can do everything properly and send targeted visitors!