1X is very nice on a mt. bike when you ride trails with a lot of closely spaced up and downs, where you are shifting a lot. You don't spend time thinking about the need to shift the front and the rear into something useful. Its all available in the range of the rear. You lose some of the closer spaced gearing, so if you're favorite trail is flat and you like having tighter gearing as on a road bike, you lose that as the jumps on a 1X are much greater, especially at the upper end of the cassette. Don't buy into the idea that a 1X is more reliable as a 3X system well setup was never unreliable, just one additional cable and housing the change during maintanence time. And its not like 3X suddenly started to suck.