I think possibly 'Jazzway' has answered his own question:- "But then, i have never had a Jazz CVT.".
My first Jazz was an I-shift and it nearly put me off the Jazz for life. My main concern was the long time it took to change gear, particularly from 1st to 2nd.
I guess most manual drivers can change gear in less than a second.
Imagine joining a busy main road from a side road. You start off in 1st, get half way across the junction, when all acceleration stops, whilst the the gearbox 'thinks' about changing gear, which I submit, puts you in a very vulnerable position.
Fortunately at the time I had a friend with a new CVT Jazz, and for me the difference was like chalk and cheese, a very smooth take off and no lags in acceleration anywhere.
So, as soon as I had saved up the pennies I swapped to a CVT and have never looked back.