Hey Arturia,
I never need to mute all of my drums at the same time. What i do need to do is jam and perform with muting and unmuting drum parts. Can you make the "mute" button on the drum sequencer enter into a "mute mode" where the drum parts can be muted and unmuted without having to hold anything down? And in this mode if the muted parts were dark and the unmuted parts were lit up with the LED that would be a great addition... Maybe the "drum"+"mute" could be the "mute all parts" function? Amazing product! could be slightly more amazing and musical with this small change!
Love You!
Brett