THE GUN BAM-BAM!
As this thread is a sticky, I don't think the necro posting applies. And I am glad to see any contributions and additions to the limited history and use of the 3906.
As to why a 3906 rather than a 3913, speaking for myself, as I owned and carried both at the same period in time, the added weight of the 3906 made it a lot easier to shoot fast and accurately. Especially one handed as one might have to in a close contact incident.
And the extra weight also gave the 3906 some value as an impact weapon too.
Regards 18DAI