I've contacted support about the upgrade. He says it'll take about an hour (it'll be an upgrade from 5 to 6 and 6 to 7). During which time, web and database services will be intermittently available.
Of course it makes sense to have this done in the offest of our hours, but it wouldn't be gracious to put him out too much. Saturday is our lowest volume day -- are there any objections for picking a time next Saturday morning?
I'll shut the board down, do a backup, let him at it, and open it back up -- I don't think it's safe to have it half up during the pauses in what he's doing.