I'm 6'3" and very long limbed (arms and legs). I haven't really tinkered much with the sumo stance, but if I drop my hips low in a heavy DL it puts a lot of strain on my knees vs. the high-hip position. The latter generally feels much cleaner to me, although a trainer at the gym recently told me my knees "must" be bent past 45 degrees.
"Use what talents you possess: the woods would be very silent if no birds sang there except those that sang best." —Henry Van Dyke