I'm about as hardcore AI-purist as you get, and I don't think it's that much of a change.
Here's something to chew on, Jon, I don't know if UBB allows this (PHPBB does) but you can have board themes. If that's possible, make a new school/old school and have it a preference set.
Offer two and only two. Just the old look and the new look. Let us choose.
Once again, I don't know if this is possible with UBB. But it would be nice.
If not, the current look is very sleek and nice. I dig it mucho.
Applenut, it doesn't feel like AI because there isn't enough good content.