I don't know what the risk is. Considering that it's probably an off-the-shelf solution designed by B&O in Europe, perhaps low. The NRTL thing depends, among other things, on your insurance carrier. Still, I would never buy any amp that didn't have NRTL safety certification.
But in discussing it we're implying that non-compliance with the law is OK. As a digital product without FCC certification, this product is not in compliance with federal law. On that grounds, it should be rejected by civilized people.
As for 12-channel alternatives, I don't know the market well (and ended up buying a 7-channel Sherwood A-965, because I only needed six channels) but a company called Episode Audio has a 12-ch class D amp that's properly certified by both the FCC and an NRTL. Don't know how much it is, though.
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog