My revolver was always a 4". An early mentor told me that when it comes to drawing and firing in a split-second situation, "that extra 2 inches will get you killed." I do know that a ramped front sight is the only way to go for a duty revolver... when shooting PPC as a young officer, I had my speedloader case too close to my break-front holster. The vertical surface of the Patridge front side got caught on the edge of the (snapped) speedloader case flap, and I lost several seconds (and probably a few points!) on that relay.

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LEO since 1981.