We're developing a site for a client right now and my boss (designer only) is once again making me increase letter-spacing on the text so that it looks 'prettier'. I am of the firm belief that this often causes eye-strain and hinders readability in body copy, but being the boss, she is of course always 'right' until I can provide her with examples showing why she's wrong (generally pretty easy). In this case, however, I can't find any articles talking about eye-strain and kerning, so I figured I'd ask what you guys think about the issue of increased letter-spacing in web text.

Take a look at http://sparktoignite.com/allograft/process.php and tell me how you feel about the body copy. We're using font-embedding, so you'll only see the proper font in FF, Safari, and Chrome. Let me know what you guys think about the readability and eye-strain caused by the font. My boss currently thinks it's 100% perfect (she wanted the kerning increased further, but I talked her down luckily).