I have no experience of them, but there's no reason for them not to work well I suppose. But it seems a bit of a strange thing to do if you are talking about brand new kit. I would have thought you could buy a full groupset much cheaper than mixing & matching components.
What exactly do you have in mind? Personally I love Campag road gear, but if I was buying a new setup I wouldn't want to have anything below Chorus because the lever design on the lower groupsets don't let you do the same multiple gear shifts with one stroke of the lever like you used to be able to do across the whole range on earlier designs. And then It's starting to get expensive, whereas it sounds like you are wanting keep the price down. The latest Shimano 105 groupset looks like the best current price/performance offering at the moment I think. Although I would rather look for good second-hand high-end Campag stuff personally like - but then I'm just a mad old git.
its just one of those crazy ideas i get sometimes
full groupset (of anything) is out of my budget.
but new campy triple veloce shifters (somewhere between tiagra and 105 i believe) are about 50 quid cheaper than tiagra triples and about 100 quid cheaper than 105 triples
and i already have a 10 speed 105 RD, which means all i would need is a 10 speed shimano cassette (which is buttons compared to a campy one, and with nicer ratios for a fat bloke from Consett), and the shiftmate