Sorry for the late reply.
I ran 20x10x9 ITP GNCCs for XC racing in MI this past year. I don't have much experience with other tires, but I was very happy with how they performed and they seemed to hold up great. I'm working on a 2nd XC build that has 20x11x9 Obor Advents. I don't have actual weight numbers, but the Advents are much heavier than the GNCCs. It'll be interesting to see the performance differences when I finally get it to ride and compare.
I know the GNCCs are 10" wide compared to the Advents being 11", but the amount of increased weight was a surprise. I should also mention that the GNCCs are on Hiper beadlocks vs. the Advents on GPS beadlocks, so there could be some weight difference there, too.
I don't have a perfect side by side comparison picture, but you can see that the Advents are noticeably larger.