I'm also running into quality issues with the various export features. :-/
So far, my best, yet most tedious option is to Export > Artboards to Images and do that for EACH of my layer comps, then assemble them into 1 PDF in Acrobat
In an ideal world my 1 PSD, with 3 Artboards and 12 Layer Comps, would kick out 36 individual, crisp, pages in 1 PDF.
I'd like to use layer comps for different pages and artboards for different device sizes when doing UI work. Unique artboards for each adds up to a slow, tedious to use document and it's hard to adjust global things that don't change on every page like a header graphic. There's so much redundancy.
Layer comps don't handle canvas size changes, so that solution doesn't work alone either.
A script that did both would make a solid workflow for UI/web/app designers achievable! As it is now, I still have to keep desktop/tablet/mobile comps in separate documents to be able to export all quickly. It would be so nice to have one document, three artboards, and one layer comp for each state or page I wanted to show - and that I could export them out in a click!
Im adjusting the script to make all options optional, i also got transparency working now