Which engine did your Jazz have Bungle, 1.2 or 1.4?
While I totally agree with your 'about town' comments, I have to disagree with your findings regarding faster roads. We had a 1.4 Sport version for a couple of years and I was always amazed by its motorway refinement for a small car -happy as the proverbial sandboy at 70-80mph - we always arrived at our destination feeling very calm and relaxed.
It's no wonder it scores so highly in all of the surveys.
Also, I reckon there is more room for a front passenger to stretch out due to its deeper foot well legroom compared to the Civic.(or a CR-V for that matter)
I do not think that small car necessarily equates to poor high speed refinement.
This week's Auto Express features the new Mini Cooper and I quote "In fact,whatever type of driving you're doing, the MINI excels, with refinement at motorway speeds being especially impressive"