First off I love your builds and my router... I had excellent luck with 59 and skipped all the 60 builds. 61A2 seemed very stable and I just upgraded to 61B1. So far still seems very stable (all on my RT-AC5300.
I do have one comment (that is not new to this build but still needs mentioned in my opinion). If I have QOS off the Traffic Analysis page seems to count both upload and download correctly. If I turn Adaptive QOS on (and I have all other settings such that CTF is also on) then I see the following.
On the Traffic Monitor screen Real Time always shows almost exactly the same number in the Reception and Transmission areas (even when this is not true) and on the Daily Screen the Transmission number will always be just a little higher than the Reception number (Almost to the point where it looks like it is including all the Reception and Transmission data in the Transmission number but I'm not sure that this is true).
Traffic monitoring requires CTF to be disabled to be accurate. Asus inserted a notice about this on the traffic monitor page. Nothing I can do about it.