If what you're saying is true, that's a bit disappointing, but it may also target a different segment of the market than folks like you.

FWIW over at http://OfferLetter.io, we spent a lot of time figuring out the right pricing model - We let the candidate choose either %-contingency-on-increase, or flat-fee. This seemed to be the best route for incentive alignment. If you have any other ideas for pricing models that work well, do let me know! mallyvai-at-offerletter.io

[We discarded the %-of-net-compensation model - it felt too extreme, and it wasn't clear we could add sufficient value in every case.]