Another update. Phone is functioning fine, still no issues with slowdowns or freezes. One small but annoying issue has cropped up, discussed here:
google play store - Android Marshmallow keeps moving apps to internal storage after update - Android Enthusiasts Stack Exchange
Basically, based on a particular flag in the apk manifest, some apps will not automatically migrate to adoptable storage during setup. Many of those apps can be manually moved to the SD card. However, when those apps update via the play store, they will move back to internal storage. So, every once in a while, I move updated apps back to the SD card. Not a big deal, and a problem that should go away as developers get comfortable with adoptable storage, but not quite " set it and forget it".
Posted via the Android Central App