I've had my 505 for 10 months, and I went from liking it and finding it convenient to absolutely loving it. I'm finding it harder and harder to deal with pbooks because I am getting very spoiled with the size, weight and convenience.
The reason why I went from liking it to loving it is that I discovered Mobileread, which resulted in my finding out about Calibre, and then Convertlit. Having these two tools means I have more book buying options, which actually may not be a good thing.
Anyway, I'm going to extend my 505 love to Mobileread love. I may not post much, and I wish I had more to contribute, but I appreciate everything the experts have provided, and am extremely impressed with this community.