I'm definitely going to be testing this on my own server. I've been looking forward to this since it was annouced.

One bit of constructive critism: You got to lose the Mailpile font (which looks like some bastarization of Museo). I know it's part of your branding, but it has no place in the UI. Not only is it much less readable than almost any simpler sans-serif, but the huge x-width makes the text take up so much more space than it needs. Your backup Helvetica Neue with the weight toned down to 400/500 is a huge improvement alone.

Keep up the good work! This is a true service to society.