Excluding hamstring/glute variations to build legs, I really think they are overrated for building a good back. I have pulled in the upper 6's but i did it because i was really into my numbers for a while and during that time my back didn't look as good as now that i hardly ever pull. Only changes i really ever noticed were it brought out my obliques a bit. I don't know any bodybuilders in real life who pull aside from a few natty ones that basically powerlift and with all due respect aren't very big. Sure for a new lifter trying to pack on some mass it is very helpful, but once you get to a respectable size, say 5,10 220 and 8% bodyfat I really don't think it will make a difference whether you pull or not especially if you barbell squat.