What do you use the extra flexibility for? I have a Kobo because I don't give money to Amazon. I wouldn't know what to do with it other than buy books from kobo.com and read them.
I purchase a lot of independent ebooks that come as epub files. You can send them through amazons kindle service or convert them with Calibre, but I love being able to just drag and drop any file I want onto it. I've purchased books on the train and dragged and dropped them onto the Kobo mid ride.
It's mostly because I like owning a more portable file.