If I had a mountain bike 1x would be preferable. My beach cruiser has 1x7 and is just fine as well, though it hardly sees an incline. I have rode 105 11 speed. I may be too accustomed to 5 - 7 speeds, found myself skipping cogs a lot. 50/34 front and a 28-32 low cog rear, and I seem to work with it ok and keep cadence and speed decently. Meanwhile, unless I buy something new or move back to mountain country, I don’t see myself moving on to a 10-11 speed cassette.