Hi,
RS-9? the Behringer RS-9 Rhythm Sequencer?
Yeah that’s one way to solve the misbehaving Nano gate sequencer but its not a DIY Gate Sequencer 
Im using a Korg SQ-1 sequencer (which is also no DIY) but just for convenience and I’m planning on replace it by something DIY. I try to be as analog as I can. Sometimes you need something like a controller which is hard to build yourself like Arduino Nano. This makes things a bit easier with less parts and stuff I know, but if it is possible I prefer to build it myself.