You're right about Arno and Default after examining them closer and not between other fonts. I did more checking with the Sony default against Arno using the Windows font viewer for Arno, and while they do look pretty similar, there are certain letters, like the "j" that are distinctively different and it looks like the Arno font isn't loading for some reason. I tried renaming the files, using files from my Windows directory that I know work in applications on my PC, and couldn't get Arno to load on the reader for some reason. Really odd, never ran into that before.
I'll give your css a try and see if it'll overwrite the epubs with embedded fonts, thanks. And glad you gave PRS+ a try and like it, I thought you'd like the ability to swap fonts so easily.
Edit: I was able to override all embedded fonts (all that I've tested it on at least so far) by adding just the following to my .css files. I haven't needed all the spacing entries so far, but saved your complete file in case I ever run into instances where it is needed. Thanks for the info about using !important.
Code:
html {
font-family: LexiaDaMa !important;
}
.mainBody {
font-family: LexiaDaMa !important;
}
.calibre {
font-family: LexiaDaMa !important;
}