Just build a new theme with zen. It all went smooth. But being more a techy then a designer I only tested with FireFox, Gnome Web Browser (Gecko 1.8), Opera, Safari and forgot IE 6 which I have through ie4linux. Guess what ... it broke with IE 6.
Yes I know ... IE is out there for real so you better test. But it is a drag for sure. The designer uses IE 7 where it looks ok. So maybe in the near future we are saved a drag or two :-)
Talking with chx on IRC regarding the issue http://drupal.org/node/211182 => Updates run in unpredictable order => Drupal, update system, normal, active, 3 IRC mentions
chx has written some testing on DFS in the drupal sandbox. The nice answer "noone stops you from taking the weights.php from my sandbox and run with it." and these http://drupal4hu.com/node/39 comforting words I guess I have to 'go for it'.
But I first needs some 'steps to reproduce' the issue.