I once had the RRS BH-40 and BH-55, but I found that the double drop down notch was a fatal flaw when used for landscape and macro photography. IMO it is much better to have a single notch that you can keep lined up with the lens, and, in fact, RRS has changed the BH-40 so that is now has a single notch. I expect they will eventually change the BH-55 as well. I love the Arca Swiss D4 for landscape, architecture, product and macro work, and use the RRS gimble head for wildlife and stitching panos.