Just looking at Moonglu (http://www.moonglu.com/shop/category/wheels/mountain-bike-wheels/) and they list the Stan's Arch rim as "filling the gap between Crest & Flow".
For some reason, I had it in my head that the Arch was an older model of Stan's rim, and needed drilling & additional faff/rimstrips to set up tubeless with non-UST tyres - am I wrong on this?

