Have you thought about ordering it from Canada?
Not sure if it's possible, but they are less then 320$ here, and our dollar is closer to yours.
I was in the same boat as you, and in the end I went with the Sony.
Originally I bought it because of the price, it was cheaper here, although that doesn't apply for you, and as much as I would like dictionary support, I would buy the sony even if they were the same price now.
four reasons I prefer the sony.
1. BUTTONS. The slow refresh rate means that it takes forever to get anywhere, having tons of buttons speeds up book selection and navigation a large amount.
Especially for early adoption of technology since new tech is usually slow, lots of buttons are good
Being able to use either the buttons on the lower left or middle right are nice.
2. Caliber. This is probably the most important part of the sony reader.
absolutely and without question, the sony library was terrible.
The virtually nonstop updates, a clear and efficient interface(even if the really good functions are easy to miss for ages). Oh yeah, and the fact that it is the computer equivalent to a garberator, throw anything in and out it comes nice and ready to read
nothing else will do the job for organizing and converting to one format if you're working with piles of formats and so on from all the free authors around.
3. See #2.
4. The metal chassis, it looks slick and survives well.