I have the Kindle DX and it is my primary e-reader, but I also have an I-Pad. The e-ink on the Kindle is easier on my old eyes, but navigation isn't as easy as it could be. I use Calibre for format conversion, but wouldn't suggest buying an expensive reader that required removing DRM. Even if the legal and ethical issues don't bother you, it puts you in a technical battle with your software sources.
That said, I am waiting and hoping for the new generation of e-readers to become available in big screen models. It worries me to have as my primary e-reader a model that may lose technical support in the near future. Reading other posts on this site I suspect that the M92 is already having that sort of problem. If you intend continuing to use Amazon as your principal source of books you (and I) ought to lobby them for a modern replacement for the DX