So it seems that I spoke too soon. I just tried the trick mentioned in pg. 14 of the manual I linked to previously, but there's quite a few differences between the nav and non-nav systems besides just the GPS capability. To get to the User menu in the non-nav, you hold down OPT for more than a couple seconds. For the nav, you hold down AUD for more than 2 seconds. Unfortunately, the two menus control different settings (compare p.14 in the previous link to the NAV manual, pg. 97) No user memory option can be found in the NAV's user menu. Holding OPT down for more than a couple seconds does nothing for me.

So with that said, I'm still trying to figure out how to access the NAV stereo's user memory, if there is one. Otherwise, I'll have to conclude that my Crossfire's ghost really, really likes techno music and 103.1 FM.