To me they make most sense on a 5 string because the M4S is so large and that many large tuners looks real busy and hangs a bunch weight on the end of the neck. I weighed my tuners from the MkII 5 when they were removed and I came up with 1.7 lbs of weight. But on the 4 string I like the big ear look.
I'm sure mine weighs even more at the headstock and appears even more "big-ear"ed, because of the dumbo tuners Pete used in the early 90's.



