Apparently this was just a very long driver download/update. I have never had a Dell update that took anywhere near as long in the year I have had it. Seems fine at this point.
System restart was performed when requested, and appeared to restart fine. However subsequently trying to run Dell Command Update, the splash screen appears, then disappears, without checking for updates or showing another screen. Support Assist will start and appears fine, until checking for updates, when it reports "unexpected error" .
3450 after this weeks Dell SA update shows error