There is an extra layer on the Paperwhite, as it uses a capacitive touch screen, not the infra-red that the others use. It does appear to make the touch screen more responsive, and there doesn't seem to be much of an issue with the degradation of the text quality. The problem you might have with the Paperwhite is getting one with a 'good' screen, as there are a number of people unhappy with pink or green hues noticable on the screen (and many others that maybe have minor discolouration but don't really notice it). If you get one with a good screen though, none of the concerns you have about the screen should be an issue.
Have a look at the customer photos on Amazon (link here
to UK site as that's the one I use!), and you'll see some pics showing the problems but also those showing perfectly good looking screens.
The Paperwhite (and the newer Kobo, the Glo) use a higher resolution screen than all the other ereaders, and while many people have said they are happy with their Kobo Mini's it does use a slightly lesser quality pearl screen. I've had a play with three different Paperwhite's in shops and the screen has looked pretty good on all of them to me. Then again, while also being quite impressed with the Kobo Glo in a shop, the Mini next to it didn't look to bad to me either!
The Paperwhite is a bit heavier than the Kindle NT you had (and the Kobo Touch) so possibly will feel that bit more substantial.