I think that campag have enough history of making parts for serious racing machines and innovating new stuff to trust their kit; I have to say I have had similar feeling when looking at SRAM parts, as I have only really known Shimano over my many years cycling, but until we try other makers we'll never know...!
It's like comparing Window's based PC's with Apple desktop machines: just because 90% of the world has a Windows based machine, doesn't by any means make them 90% better. A much larger number of mass produced, and mid range bikes have Shimano parts fitted than Campag or SRAM, I would imagine, but those who know what they are looking for won't necessarily just go for Shimano. This has gone into bit of a ramble, but hopefully you know what I mean.