I have used both and have noticed that with the all steel wheel you tend to get a lot of chatter between the wheel and blade, Which tends to make grinding a little harder less smooth and uneven. On the plus side the all steel wheels are considerably cheaper.
Personal opinion, Treat it as if it was the biggest show ever. Get a sign made, have business cards ready, use a nice table cloth, be engaging, don't sit down or work on any projects.