I can only attest to the difference between small-time lawyers and big-time lawyers/trusted advocates of huge companies, who do business negotiations all the ti

I can only attest to the difference between small-time lawyers and big-time lawyers/trusted advocates of huge companies, who do business negotiations all the time: The difference is huge, and it absolutely makes sense to hire a pro negotiator. It ultimately comes down to price/terms. And an experienced negotiator can make a huge difference there. For you, it's a once-in-a-lifetime situation. For them, it's daily business. Guess who's better at it. EDIT: ah well, misread that as "Ask HN". My bad. P.S.: I personally don't think it makes a lot of sense to have an investment banker as the lead negotiator. They sure do add value in some cases, but most of the issues arising in share purchase agreements are better entrusted to lawyers.