AQM, you would probably be surprised how quick the leather would let go on the edges. Also the hide on those two-sided hammers doesn't last very long if the hammer is used in anger.
"Original equipment" on my old 4/4 was a 10 lbs. copper Hammer.
In my opinion best choice is the tool from the MG site, which is also available on the website of angloparts
http://www.anglodesign.be/images_ap/Toolcatalogue_2005.pdfFrank
