Thanks so far for the input.
I'm pretty well-versed on hinting and anti-aliasing (design background), but it's hard to predict the results on the PRS-505 without trying them out.
I agree on the slab serifs so far, as Chaparral Pro, Centro Slab, and Grandesign Neue Serif all seem to work reasonably well, with the sweet spot being around 10pt. My default font is Chaparral Pro so far. Haven't tried Archer yet, but maybe I will give it a go later.
Fontin works alright, but not great, as with Gentium Book.
I don't seem to have a copy of the Caecilia font, and yeah I don't think I'll be going out of my way for a copy.
I am not a sans-serif kind of guy, but I did find Candara remarkably readable at modest font sizes. One of my favorites so far on the PRS-505.
It really is too bad that I can't get the most out of my Garamonds or Caslons.
I suppose it doesn't really take away much from the convenience and portability, but it'd still be nice to get more visually out of the fonts, rather than just an expensive generic text reader.
I'm gonna keep looking, hope more people can chime in too with their experiences :
