If you separate the networks to 2.4GHz and 5GHz it will literally mess up every 2.4GHz device in your entire building. Even asked neighbors.
Tested on 8 different computers each having a Logitech K800 and an M570.
Tested with both paired to one receiver and one receiver for each device.
Seriously, it messes everything up, even TV remotes @ 2.4GHz.
It doesn't interfere with anything when in combined mode.
Leakage needs to be fixed.