yeah lots of people jumping on wagons and repeating what someone said about it not having an effect, but no hard proof
just proves that theory isn't as good as actually trying something. The same person also told me and many others that there's no point re-working a Williams head as they flow really well (which they do) and dont get any gains... which isn't true, as Port Formance did back to back RR tests on one of their heads and the difference was around 10bhp. There's a thread about it on Williams Clio somewhere, Port Formance even put up their flow data showing there was nothign to hide, sadly some of the other tuners getting involved made a promise to do so but sadly nothing ever came of it. Wont speculate as to why though.
I'd be sceptical to believe something does or doesn't work until it's been tried, I've driven the GDI demo on single ITB and it spanks the living crap out of my car on full ITB's. I dont think I'b be saying the same about it on stock TB, as the spec of the car is similar to another ITB'd car and it's making around the same power.