I agree with Gooner. Get a whale and you will mock CPA from then on. I remember doing a retrospective calculation of my commissions if I did a CPA instead of a rev share. I would have made less than half if I did cpa (using the highest CPA I’ve seen).
I know some larger US affiliates prefer the CPA deal for legal reasons, which is fine. If you are only looking for revenue then rev share is the way to go in my opinion.