Design changes are are really hard problem. You will piss off a certain percentage of users - it's unavoidable.
There's also a lot of risk surrounding a site redesign. There are definitely sites that have redesigned and I've stopped visiting them. Not a conscious decision, but once you lose that feel, it's hard to come back.
MacRumors redesign has been a stop and go process. As WildCowboy said, we have a lot of back-end changes to be done.
I guess the best thing is that we've made some progress in the past few weeks. Design is coming along. It's not quite there, and the backend changes still need to happen. But, realistically, I'd like to get this done in the next couple of months.
arn