I have and it hasn't really done tooo much to notice a lot. I got the mild cam with a .414 lift I believe. If you are carbed then I would suggest getting it, as my F.I. sucks anus :p.
those cams on ebay are just regualr stock cams shaved. Save yourself some money take out your cam take it to the machine shop and have them shave it. It would be less than the 130 or whatever they charge.