Finally plucked up the courage to upgrade my main machine to Jaunty and it was an absolutely painless process. Even VMWare is working fine after the kernel upgrade, and that’s the first time that’s ever happened.
I still get a 20-30 pause between the gnome login screen and the desktop appearing though. Something that’s been installed and removed in the past is bugging it out, and the only error I get is a gnome-desktop-panel timeout one. The problem is that this has been related to a Compiz/Nvidia bug – which isn’t the one I’ve got. A clean install is probably the only way to fix it.