Ok, it seems like your latest patch has fixed the regression. Here are the results I got with no patches (I reverted the patch that caused the regression):
To test the behaviour with multiple stations downloading I ran an iperf3 test on my smartphone at around 150 seconds, hence the latency spike and drop in throughput. Here's also a close-up of the area where the ping is more stable:
And these are the results I got with the original patch and the fix:
It actually looks a bit better than the test without any of the patches. And a close-up:
Which look pretty good! What I don't really understand though is why the ping climbs so high when I run a concurrent download on my smartphone. This seems to be an issue with AQL, unrelated to your patches, which needs to be looked at.