Is it OK to only replace the small ring on an XTR crankset? At the end of last year, I was getting chainsuck in my small ring. I am replacing the cassette, chain, and small ring. The middle ring looks pretty good and the big ring looks good.

Will this be a problem with mismatched wear on the different rings?

It seems like you already have uneven wear, which is perfectly normal, given your specific riding habits and locations. That is why the chainrings are available as single units. There is no reason to replace your big ring if you never use it, and if you tend to ride big hills, you will go through your granny faster than the middle ring, so replace only what you need to.

Go for it. If you do a lot of climbing, you will wear the little one out.