Bragging rights have nothing to do with my tool decisions, if you have found that 1.5 mm difference doesn't effect your ability to use 3/8 drive impacts and the extra mass seems to hit harder I'm listening but for me a millimeter and a half would determine if the socket would rub/scratch a valve cover, fuel line, etc and since people pay me to fix their stuff not scratch it that would be helpful to me.
As a side note the reason I'm interested in the Duo's is I'm building up my 3/8 impacts and doing away with most of the 1/2 inch in favor of 3/4 drive so I was thinking of getting the Duos as I would rarely use any chrome sockets when I'm done.