I don't know that 10sp needs any more adjustment than 9sp., so I wouldn't worry about that. Supposedly 10sp wears a noticeable amount faster than 9sp so you'll end up replacing at least your chain and possibly other things more often. I think that on a 1x9 vs. 1x10, it may be worth it depending on personal gearing preference. If you're riding with 2 or more chain-rings then I don't think it makes much difference if you ride 9 or 10sp in the rear because your granny will give you the easy gear and you can gear the same for speed on downhills. 9vs10 will just be a matter of how many overlapping gears you want in the middle. But hey, that's probably what a lot of people said when they hit 7 gears in the rear and the same thing that our kids will say about 16vs18 gears in the rear, right? But, as I said, to me it seems like we're getting to the point where the gears are close enough already that 9 vs 10 is mostly a matter of parts being made of thinner metal and wearing out faster. Is that one extra gear in there worth the extra time and $$$ into maintenance? If you race and make money from biking and it's worth the extra time and $$$ to have a potential tiny advantage then 10sp is worth it.

I ride 1x9 on my MTB and 2x9 on my road bike. I'd go 1x10 on the MTB just because "why not" if the maintenance/cost were the same, but it's not worth the money to me.