It depends on the rider more than the locale. Spokane is plenty rocky. It's plenty rocky where I am too. Some of us can make soft rims last on our trails. And some of us can't. It doesn't mean you're a hack. Everyone has a way of going fast, not everyone is a float/skim rider. You must know this, eh? Think of the DH bike selection available... some are better at plowing, some are better at popping/skimming.
Mavic makes strong burly rims but when I was a lower-skilled rider I trashed Mavic rims regularly. More recently my trail bike had a set of very soft Salsa Delgado Disc rims (on Hope Pro II - making it relevant here!) and I rode them on our roughest trails and on our only DH race course, which is brutally rocky in many places. They never got trashed. If it matters -- I weigh 150.
Yeah, I understand that I was just trying to say with some trails where there is no "smooth line" just rocks combined with a lower psi (24-30) for races, sidewall bends are going to happen on a soft rim like the 5.1d. Making them not ideal. PS, I do have a plow bike(Judge).