Thank you for all the detail! After a lot of looking around and soul-searching I think I probably will go for the Kindle despite how much I dislike the proprietary thinking behind it. The choice in the UK seems to pretty much come down to Kindle vs Sony anyway, and the Kindle is considerably cheaper. If I can get non-Amazon indie stuff (and fanfic!) to work on it, I'm not too worried about buying from other stores.

(Since originally commenting I've been reading a lot of the links you've posted in this comm about indie publishing, and all at once realised there's a whole world of non-DRM stuff out there, so a lot of my concerns about jumping either way have eased. Also, I am now more excited about writing than I have been in years, because suddenly there's another option for my influenced-by-anime-epic-fantasy-with-incidental-gay-people stories. So thank you!)