I recently built up a new bike with Easton cranks, using 46/30 rings. So far, no complaints. They've got a modular system that lets you swap spiders (or integrated rings). On the original subject, I don't think this could be used with BB90, because Easton cranks have a 30-mm diameter, and the OD for BB90 bearings is 37 mm. You'd need to have little tiny ball bearings in the cartridges to fit the remaining space.
As Unterhausen said upthread, 46x11 is a big gear (though admittedly, a 46t big ring looks kind of puny). When I got started in cycling, 52x13 was the biggest gear you commonly found. 46x11 is bigger than that.