With luck you won't notice any difference, but the reality is that some scripts might have problems. I don't anticipate anything that I can't fix quickly once the problem's been noticed, but if the change happens while I'm in bed (or, say, at the match on Sunday) it'll obviously be a little while before I'm able to sort it out.

Also you might find that the most recent additions suddenly disappear. This will just be a consequence of trying to keep both the old and new versions of the site going alongside one another until the old one stops being accessed. Again it shouldn't take long for things to be back to normal.