granted you lose the long battery life, but this ASUS Convertible Tablet is in your price range and will not carry any issues in terms of document compatibility issues because you can install pretty much any software:
http://asus.com/product.aspx?P_ID=KIqtSJ1aVsmVpeqS
http://www.amazon.com/T91MT-8-9-Inch..._ob_pc_title_0
Of course more research is needed but given your time frame, budget and what not, I don't feel any of the dedicated ereading devices that exist today will give you problem free ability to do your research. In fact you will likely keep fighting against the flaws in most devices and waste a lot of time on working around those bugs/flaws/funky way of doing things.
I also sense there will be even more of this sort of device released at CES but remember the one thing about newly released hardware is there is a buy-in premium for new devices and all new devices are an unknown quantity reliability wise. So, I think I might not recommend waiting too long after CES and for looking outside the dedicated ereader device market. Or go with the DR1000C then sell it when you are done with your degree, you will not lose much and then you can buy the flavor of the month device.
No matter what decision you end up making, it has to be difficult because the ereaders are so very close, especially the DR1000 and it's ability to work with multiple open documents. A more PC like device gives all of that and more...for less though as everyone has mentioned, the major trade-off is batter runtime.
And YES, the large screen Pocketbook device might be the real front runner and they have the advantage of a solid firmware in use already...that's why I originally suggested the wait until after CES because comapnies are really being secretive about what they are going to offer...it's sorta fun to watch for sure!
