Just want to add that I just updated to the 374.41 Beta1 release on my RT-N66U.
No resetting of settings, just flashed over 374.40 as RMerlin has recommended.
I think I'll miss the cmd page, but I can see the reasoning behind removing it for security reasons. I'll learn to use the new, recommended procedure.
Here is the few data points I have to report so far:
Usage: no exotic setup - just routing, wireless and wired.
374.40 was not rebooted since it was released; no need.
I tested (via Ookla speedtest) the ISP speeds both before and after rebooting router on 374.40 firmware - no difference. Easily hit my 50/10 ISP speeds (52.89/11.35 @ 8ms) both times.
After flashing 374.41 Beta1, the increase in responsiveness was noticeable immediately.
Ookla speedtest showed 52.79/11.36 @ 7ms but what struck me was the consistency of the live graphing (the Beta 1 firmware has a very positive effect) of both download and uploads.
I don't expect any issues with my very basic use of my RT-N66U, but I will be able to test with an RT-AC68U too later this week.
RMerlin, thanks once again for your focused commitment to improving the Asus routers.