There is a MASSIVE difference in throttle response mate. To be honest, it's this very responsiveness that I enjoy as much as anything else about the ITB conversion.
In terms of feeling the difference in power, it is noticeable. However, you do need to be realistic. Sure, the Clio is a relatively light car and all but (as one guy said to me) you won't be chasing down Lambo's anytime soon... So just go into it knowing that it's going to cost a fair whack and be realistic in what your gains are going to be real world
Personally I noticed a huge difference in power. But there was a reason for that. Without going into detail my engine was screwed and only made in the 150's so picking it up fixed from TDF with it pulling 200bhp the difference was 'significant'