personnaly I would avoid pinspots and profiles as I feel the effect looks very yellow and gives the impresion that you havnt dusted the ball lately , the abilaty to adjust the focus is also important, fillament lamps can leave you with lots of filament effects floating round the room , I would always aim for something giving a much whiter light such as a discharge lamp, goldenscans, miniscans, scans without the mirror or pro 400s are all excellent but expensive the abstract colour flood I suggested earlier is a cheap version (£100ish)of a pro 400 and gives a nice white (or coloured) even spot and can be run off a stand alone controller I would use a minimum of 2 if the audience only see one side of the ball or 4 if they see all round