I recently made the switch from the 505 to the kindle. No regrets here the kindle is a great device and I really liked my 505 at the time
There are tools like calibe and LRFTools that do concert lrf files to epub/mobi. The shifted format is good, but not as good as shifting from epub/lit/ereader to mobi.
One word of advice is to always buy a shift-able format like mobi/lit/epub, even if you decide to stay with the 505. When I had a 505 I use to buy mobi, it was a pleasant experience that I do not have to shift half of the books I own.
I'd recommend you shift a book and see if you are comfortable with the results.
=X=
|