I will suggest you ask yourself if your reference manuals and such depend on color. If yes, then you need to wait whether you want to or not, no greyscale panel is going to be worthwhile when you depend on color. If you can live w/o color and the whole lack of annotations thing on PDF's, maybe...but know within the next 3-6 months actual production color devices will begin hitting the shelves, including those based on the PixelQi panel.
But if you need such a large format reader now, the DXi is not a bad choice given the options currently to be had. And remember even if color or something you like better comes out this year, you will not lose much on the resale of your DXi...also, hunt the Amazon Warehouse for refurb'd Kindles. Not sure if it is over but if you also like audiobooks anyway, there was/is a deal where you sign-up for a year of 1-audiobook/month at $14.95 and get $100 discount code for a variety of Amazon devices including both Kindle versions. I had a thread about it in the "Deals, Freebies" section here on MR. It's a nice deal IF you already enjoy audiobooks, I do so I just created a new account and got my K2i for $159...I would have gotten the Audible subscription anyway.