[hoichi]

Have Kobo, love Kobo, don't mind bying from Kobo (don't see why is that any different from an Amazon/Kindle situation). That said, I buy (or download, when it's public domain or something obscure and out of print) from other sources too, so I have to use Calibre for that (well, you could just copy files, of course, but that's too much manual labor for my preference). And since I manage my bookshelves with Calibre as well, it's so much more convenient to keep all my library there. And you just have to use Alf to add DRM'ed books to Calibre.
So there. My OCD is not that bad and I wouldn't want to end up spending more time managing my books than actually reading them, but I believe, in the long run setting up a sensible system with Calibre rather saves you some time than wastes it.

EDIT:Blimey. Just noticed the thread is actually in the Kindle forums. Anyway, I think my points are still valid.