I've had the remote for a couple of years now, and it's always been hit and miss. Sometimes it works, sometimes it doesn't work. And this can change during one drive (to work for instance). I put in a new battery and it worked constantly for about two days, then back to intermittent.
The other week I removed the screen, grabbed my little home made tools and removed the head unit. I then checked the wires and connections. All seemed ok (I am not using the connectors you suggest, but I may soon!) so I reinstalled the head unit and screen.
Since then it has worked flawlessly! Maybe the connection was getting stressed by the way it was crammed in there before, and now it's better? I don't know, but it's working for now so I'm not going to touch it until it fails.
It is very sensitive. I can turn the dial one click and the volume can change from 0 steps to 4 steps of volume. And the delay is a bit annoying. But, it's still way better than swiping down on the screen, then touching the Volume slider, then adjusting the volume with the slider! Man, that is a pain. Not to mention all the time spent NOT watching where I'm going!