Looks good Steve, good job.
It'll take some getting used to, some little things to notice.
I too have to scroll back and forth a little bit, but only like 1 inch or so, not sure why, 15.4" widescreen laptop running 1024x768...
The only thing I don't like that the 2.x versions had worked out betteris this: When viewing "New Posts since Last Visit" on 2.x, the message name (link) and the pages within the message where all in one single row. I ctrl-click to open in new tabs (ie, I load all of the new messages in tabs by simply scrolling down and clicking each last page or message title). Now, with 3.x the page numbers are to the right of the message titles, so I have to scroll back and forth... kind of a bummer. oh, not you design there, I know this.
Anyway, good luck with the continuing work, there is so much involved in running a decent and decently modified forum!