Am I being led to believe the change is better for me?

I wouldnt sign it, im assuming your paying the equivalent of one years revenue? Quarter million or so, I'd let this contract expire and lets them think you lost interst, I'd renegotiate the terms, considering how easy it is to inflate financial projections, also that they amended the contract stating that it didnt always make this much. It sounds sketchy which would immediately turn me off from buying the company.