Looking at a new Orange, and very tempted by the option to upgrade to the Mavic XM819 UST rims. Not had tubeless before, but I've heard more about systems like Stans/No-Tubes (airtight rimstrip plus sealant) than UST. Is this because UST isn't so popular, for some reason? Or does non-UST tubeless generate more problems and therefore more feedback on STW?
And the XM819 rim- looks a bit heavier than some of Stans offerings- is it a decent strength rim, or just too heavy for an XC rim?!!

