[makincheez]

I just made the switch from the 505 to K3 yesterday. Though the Sony is metal the K3 would not , in my opinion, suffer any worse from a drop if it was in a cover of equal quality.

I find the screen quality better; slightly lighter background and substantially crisper text. I wasn't crazy about the function of the page turn buttons on the Sony; the K3 is a big improvement there. Screen seems a little less glossy to me than the 505 but then I didn't have any issue with it either.

As for "ecosystem" it's too early for me call but I am finding it easy and convenient to find free materials on Amazon that interest me. My existing library from the Sony is only a conversion on Calibre away from landing on the K3. I purchased the 3G with special offers. Like you, I may not need 3G but for only $25 more than the wifi only with offers it was worth it. Versus the $50 difference between the two versions without offers it was a good deal.

As a side note, I purchase a brown leather M-Edge Go cover and it works better than any of the three covers I had for the Sony. Should you decide to go with either Nook, K3, or maybe Kobo I think depends on how you acquire books. As for reading experience it's going to be hard to go very far wrong with any of the newer readers, IMHO that is.