Slapno, the PPM shares are tough to sell, but that changes right after the two-year mark. At least that's what I was told by my Ameritrade guy.
He said after that time, you can just sign the certificate, and send it to your broker, and they'll just drop the shares into your account. You don't even have to sell 'em at that time if you don't want to.
I may be missing a step, but the point is they are way easier to sell after two years.