When my nephew went to do the first ascent of Escudo (the Shield) in Paine - twice as high as El Cap and 110 deg overhanging - I equipped him with a tiny little Pentax MX. It held up fine in those extreme conditions, but he didn't routinely change out the batteries like I told him to do, so underexposed the potentially best paying shots, of Andean condors flying all around them during the whole 20 days on the face. Still, North Face got what they financed him for, with their logo "accidentally" in the foreground somewhere in each published shot, on a jacket arm or porta-ledge fly, or whatever. Is that 400 EDIF the 645 version or the 67 model? I have the 6X7 300EDIF and love it. Once in awhile I use it with a Nikon adapter, but mainly for 6X7 per se. But I'm in the mood for 8x10 shooting now that I'm back from mtn outings for awhile.