OK, so here's some updates for you....
The machine is running the first and only firmware that O2 have made available. I have searched around the web, but there doesn't seem to be much available in the way of big fixes or improvements. Not that I've found a need - was just curious.
Turns out that there are some subtle differences in the units, depending on which one you buy. It's available under various names - TMobile MDA Vario, O2 XDA Mini S, Orange SPV M3000, HTC Wizard, iMate K-Jam, etc. Plenty of folk have tried swapping the ROMs over from one to the other, but it always breaks more than it fixes.
The O2 packaging is something to behold. Couldn't possibly describe it without attaching a video, so I won't bother.... It's just the best box I have ever received a gadget in.
The unit is a good/reasonable size, but it's not easily pocketable. This is partly because of the thickness and partly because I daren't put that beatiful screen in my pocket without protection. The provided case is very good, if you like belt clips, but still applies a light amount of pressure to the screen. I'd recommend a PPCTechs Writeshield for the screen as minimum protection.
A USB cable is provided for synching, which also charges the phone. Worth noting that you should be using ActiveSync 4.1, not the 4.0 that the phone is provided with which is full of bugs. Wireless LAN synching has been removed from ActiveSync 4.X due to security issues. People are hoping that it will be reintroduced in the future. I've synched it over bluetooth and USB so far with no issues.
When you first boot the device, you are given three configuration options:
Corporate - very basic, with only one O2 customisation. Extra programs not installed.
Basic - Customised for O2, but not to any annoying degree. Can remove a few startup programs to make run faster.
Enhanced - Full O2 customisation. Chews a lot of memory. Best if you are on O2, and don't want to run memory hungry apps.
I've gone with Corporate to see how that goes.
More to come.