Several days ago I did the reset and reconfigure. My speeds are still consistently below what they were on previous firmware, but much better than before the reset and I haven't had any drops or reboots needed. The router also seems to be running cooler.
I've never seen any noticeable benefit from doing that in the past, but I'm not against trying it. I'll have to wait until this evening. Thank you. I'll post my impressions after doing so, in case anyone else in my position comes along.
Another noob here, and wish I'd found this forum before updating my N66U to 3.0.0.4.380_3264. I haven't collected any data scientifically, but anecdotally my 2.4GHz WiFi speeds have gone from around 90Mbps routinely, to anywhere from 20 to 50 at best. That's just doing a typical "consumer"...