Hi Kumabjorn, you're right in what you say.
That said, thanks Josieb1 for reassuring me as to how simple it is with Calibre. I've gone ahead and ordered one, but won't hold you responsible if it's not right for my needs!!
Fortunately, the Kindle has now reached a price point whereby the outlay is not a show-stopper should it prove unsuited.
I still hope to figure out what the issue is with the RTF metadata - as the Amazon.co.uk site specifically states RTF support (even if it converts it itself internally) it's a bit poor to fail on the title/author. Maybe I'll find I've just got something obvious wrong somewhere, but I won't know until around the 20th when it is shipped.
In the meantime, a semi-transparent process via Calibre should be reasonable.