I've also made a mash-up of a non-modal version:
Possible advantages may be:
- If a user changes the font size or contrast settings, they can immediately see the effect on the article. (This is partially obscured in the modal version.)
- It may be possible to automatically open the non-modal preferences window when a new feature becomes available or a user without any preferences sets comes along. With a modal window, this would become too obtrusive. (And, being opened on page load, also means nothing has to unexpectedly "pop up" later.)
- It fits better with Echo's notification windows.
Also, is the "Save" button really necessary? (This may be one reason to prefer the modal window.) Having to "save" or "apply" your settings is becoming a bit old-fashioned. You can't really damage anything by changing these settings, so there should be no need to confirm you really want to change them.