Thank you all, for both the warm welcome and the great insights on eReaders. I'm already glad I posted; after just a few posts there's already lots of info that is simply not available on review sites, store or company home pages, including other models I hadn't even considered!
@Poppa1956 - You're right about the Brady's...I went out with one, very intimidating! (*A* Brady, not one of *THE* Brady's obviously!)

@iandix - Thank you for that excellent info. The Nook's ambidextrous controls look great and I love the idea of that extra screen for navigation, but it's a little too hard to get hold of. I have family flying from the US tonight and left it a bit late to ask them to pick one up for me.

I also think the 5" models are closer to the size I'd like.
I've decided I definitely need to get my old LIT files converted and get over my hang up about them, so plan to spend some time learning to use Calibre and get my existing eBooks organised and converted. That means that at least for format support, the BBMini isn't strictly necessary. I love the look of it, but think I'm leaning to the PB360 now.
I think it was actually a review of this device by Mickey330 on this very site that put that on my radar. I love the way the screen and buttons rotate and the configuration options sound like much more useful options to have on an eReader than audio or wifi. And it's a great size too (I wonder why eInk devices all have such large borders in general?) I think for a first reader, it will be a good starting device and perhaps in the future if I find shortcomings I can always buy another. From the sounds of it many forum members have more than one already
Would anyone recommend a good vendor for the PB360? And also, any good International or UK stores for buying books from (ePub?)? And much more importantly...Black or Ivory?