The main hiccup will be that we have to unplug and rack the one server that's currently sitting upright on a shelf in the cabinet. So for 10 minutes or so free users will have one less database server working for them. But after that all should be well, then in the next day or so we'll start putting all the new stuff to use and I'll post again with details.
The other short hiccup is that we'll be moving some machines from one switch to the other. But with spanning tree crap off there shouldn't be a 20/30 second delay per port like last time we did something like this, so this hiccup probably won't even be noticable.