Well, despite the typo in my previous post, the install went fine, and I'm running Ubuntu Studio on my AMD box.
It is a curious experience.
On the one hand the OS is often very quick, very responsive, then suddenly it will run slow - usually because it's waiting for something elsewhere to happen. Maybe a download in in progress in the software manager, but whatever the reason the CPU gets bogged at around 50% and scroll bars stop working properly. Occasionally things haven't worked (typical Linux, though mostly it's much better these days) and sometimes one just isn't sure if nothing's happening or it's taking a long time.
But there IS a deal breaker.
Fonts - the mess that is Ubuntu font handling is alive and well and living securely in this version. I have installed the correct ATI driver, downloaded microsoft fonts, adjusted the hinting (not that it made any difference outside system panels) and tried different sizes, but it's all fringing red and blue, and is hard to read. Hard to understand really - almost every other recent Linux I have used has been fine with this (ATI 4850) and the Nvidia (7900GS) but Ubuntu has been consistently poor. Weirder still is that Comice basically IS Ubuntu running Gnome 3 DE with tweaks. System fonts are OK but Firefox is a tramsmash.
One more oddity - I can't open the DVD drive. Can't figure that one at all.
The system may well go to the church, not because I want to dump my junk but because this has ardour, Jack, Audacity and Lyricue on it and the church laptop is becoming increasingly temperamental (it seemed old when we arrive 4 years ago, and hasn't been rebuilt in all that time).
Some things seem really convenient, while others are just pants. Compared to comice it's all a bit crude and lumpy - there's no grace or smoothness, even though some things look quite familiar. I now want to try both the vanilla Ubuntu and Mint Debian properly installed, just to see how they differ and if they're better.
Despite that, if the fonts were finally good then I'd seriously give this a go as my main OS. As it is, the deal is broken - you are the weakest link, goodbye.
*edit*
Back in Comice. It's a *little* slower, but in Firefox the font issue made a huge difference. Might look further into XFCE as a desktop environment though.
Worth mentioning re the DVD drive that it seems to have just stopped working anyway - it's a SATA unit, and they seem to be a little temperamental anyway due to the cheaply designed connectors.