Steve's reply to my 39T chainring question reminded me of a question I wanted to ask. In reading about the new triples that are out (Dura Ace and Record) and their accompanying components, I noted that one of the new rear ders has 13T pulleys. I assume that more teeth allow the pulleys to turn slightly slower, presumably reducing wear, etc., etc.. Any other thoughts on using 13T pulleys? Is it possible to retro fit other ders with them? I assume the diameter would have to be greater. Is there any reason to do such a retro fit?

Regarding sealed bearing pulleys, whether 11T or 13T, is there a brand that is considered better?
Regards,
Raymond