I'm a Campag user.
Both campag and Shimano (and SRAM) work very well – there's really little difference in function – it's really more about preference and anyone who insists otherwise is frankly talking b******s 😉
For me, I prefer the shape of Campag hoods and the more definite (or clunky depending on how you view it) shifting – I find Shimano a bit too light action.
I ride almost exclusively on the hoods so that's also a consideration. If I rode on the drops a lot, Shimano might be more ergonomic.
"Shimano wears out, Campag wears in" is a myth. Campag wears (chain, cassette, chainrings) at a similar rate to Shimano though possibly Campag shifters are a little more long lasting before rattles start to settle in but it's marginal.
And FWIW, I do actually reckon that carbon stays make a difference – I was pretty sceptical when I got my first bike with a carbon rear end (I only got one with a carbon rear because you couldn't/can't really get many decent frames without) but I was constantly caught out by how much smoother it felt over bumpy roads and that seems to be quite a consistent difference when trying different combinations.
On my CX bike, I use Campag shifters (10 speed) to keep things consistent with my road bike but use it with Shimano cassette, chain, mechs (all 9 speed) using the hubbub method/bodge here which works perfectly:
http://www.ctc.org.uk/desktopdefault.aspx?tabid=3946