I flew for the first time since 2..8.3 and the latest firmware last night (including fresh IMU calibration). Everything seems great...the horizon seems decently level, but it takes a bit longer to self-correct after a yaw or pitch now. Maybe I'll do another IMU and compass calibration. Not a huge deal, but something I noticed.
When I updated my batteries, I received a "critically low voltage warning, aircraft landing" alert on two of the four batteries immediately after the update (P4 was on my kitchen counter, no big deal). I only flew one battery last night, but I didn't get the same warning, so that's good. Hopefully the same will be true for the other three batteries...