Thanks.
The rims are good. Pretty light and very stiff and strong. I did have problems when running with tubes as they flatted all the time. I think the stiffness of the rims contributed to this. But now they are tubeless they are great.
I've also got some Superstar XC carbon rims on another bike, are they are great as well. They are probably strong enough for AM riding, just a little narrow for wide tryes.
I did some mechanincal testing of these rims for Superstar. You can see a link to my test report on the Superstar website on the XC carbon rims page.