In the D2-style ajaxy preferences, changing the email address show setting from 'none' to any of the others (spam armoring or full) doesn't work. It probably doesn't work the other way either. In any case, on the profile page, it would show 'email not shown publicly', and the email would be absent from posts, even when the setting was to show the full address.
Changing back to D1 (old) and changing fixes the issue for both comments and the ~username page.
Also - although this maybe should be a different report - with D2, going to http://slashdot.org/help and clicking "Viewing" (under Discussions) pops up a window that should probably have a few less linebreaks.
Thanks for all your hard work, and fixing my last bug in good time...