I've been playing with two apps, LTE Discovery and Network Cell Info Lite, and I turn on the apps for a few minutes at various places I've been over the past two weeks since I've had the device. For example, at home and at work, I've only ever seen LTE band 4 and I've been traveling around NYC and Jersey City this week seeing the same band. Right after the update, I checked again and I immediately see bands 2 and 4, and when I was outside for lunch, band 71 for the first time in places where I've only seen band 4 before.
Not scientific for sure, but there's definitely a difference. Also, using the Network Cell Info app, it shows that VoLTE is active when as of last night (before I updated this morning) it was off; both times being in the same location. LTE Discovery app also has a log which confirms this (just realized that!)