I had both the dato and 1815 chrono, but I sold the dato, choosing to keep the 1815 chrono. Much debate over the years...blah blah blah, a lot of your observations I agree, but I do not think the dato is "overweight" and it seats quite nicely on the wrist, despite being heavier then the 1815 chrono. I am not a big fan of the big date, which some will argue is the Lange DNA, but hey, I do not like it, preferring the purity of the 1815. I would love to own a Double split though.
Thanks for a great end user view report.
Best, Horo