Hey, Betty, I traveled the exact same road. I still have two of the Rocket eBooks. I read all the booksI bought (when they announced they were dropping it, I bought a huge number). I also downloaded many books from Gutenberg. I still use it to read them now and then when I want back lighting to read in bed or in dark rooms, so not a total loss until the batteries finally die. It had loads of nifty features, as you know, that stupid Sony did not bother to incorporate.
Anyway, I too got the Sony Reader as soon as it came out. Despite its shortcomings, it still was great and used it all the time. Then of course, Amazon had to ruin everything by coming out with the Kindle!
I immediately bought one and have been totally delighted with it. I gave the Sony to my wife, who does not read that much, but all my books are available for her to read at her leisure.
I had read all the Sony books I had purchased, so no reason to go back and forth. However, if I had any unread ones, I certainly would have read them, using both devices. I don't think you will regret getting the Kindle at all. Once you've read all Sony's books, you can sell it on eBay or craigslist, and just enjoy the Kindle. Don't forget, almost all Amazon's books are still less expensive that Sony's.