For me it's all about the shoes. I don't like clipless for a MTB at all. Road bike is fine either way(not a racer, just ride for enjoyment). If I try riding my MTB across a particularly bumpy grassy field in anything other than my MTB shoes, I feel like my feet aren't planted on the pedals. My running shoes are outright sketchy on bumpy terrain. With my MTB shoes I can climb rocky climbs, hit jumps, and even hit some fairly big rocky descents and my feet stay on the pedals. And I don't have expensive pedals. The shoes just make a World of difference.