Later I bought another refurbished Atrix, and it wouldn't do anything until a SIM card (didn't seem to mind that it didn't have service) was inserted. At that point I was able to postpone "Motoblur" setup and install a bunch of apps. It wasn't the SIM I eventually plan to use, so we'll see whether I run into problems because of it.
But as to the Galaxy S4, I had applied the Kit Kat upgrade after purchase, and a couple of weeks ago an almost mandatory update to that came along. (Best you could do to delay was say "remind me in three hours"). And since applying that I've been 6 for 6 in success recording rides via GPS using the Strava app on that phone. Most of those six I also recorded on that with GPS Logger, though I forgot once. And I've been carrying the Atrix as a backup and recording with GPS logger there too. But that is a little tedious, and I'd like to reduce ride start overhead and back pocket bulk. And recording with GPS Logger on the same device as well as Strava only has the advantage that I get a first-hand GPS record; it was always the case that GPS failure affected it as well as Strava. (Though the backup Atrix did rescue a record of my ride at least once).