It's definitely improved. On the long hill where the Mk3 would eventually give up and noticeably change down it's now merely increasing the revs a bit like the Mk2 and Mk1 did. I'm also having no problem jumping to then holding my preferred 3,000rpm for brisk, yet efficient, acceleration. I did have one occurrence on Tuesday coming off a roundabout where she seemed to refuse to accelerate but otherwise it seems one my biggest bugbears may be gone.
Now if only there was some way to get the Mk2 style boot floor back we might be getting closer to the Jazz I really wanted. I'm going to think about knocking something up this weekend. My DIY skills are bit limited but a cut down sheet of MDF and a couple of hinges doesn't strike me as all that difficult to engineer.