Gordy and 2whlrcr (and I!) have found the weak spot -- not as good as moto boots when crushed. But for all day comfort, and walking on rock, and lever-and-peg feel, and kicking cactus, and getting scrubbed on stuff, and GETTING THE DAB when your life depends on it, yeah, trials boots are wonderful. Wear kneepads, different thread.
Really, could you even walk a section in your motocross boots?