My original post was intended just to discuss the variations in the latch arrangement. It seems that in 50 years of production they went through 5 different latches and , from an engineering perspective, it would appear that the earlier latches would be the stronger and more durable. It seems they never were happy with any of the latch arrangements but kept experimenting to the end.
My interest in the Safety Hammerless revolver in general was spiked by my recent acquisition of a couple of old books by Julian S. Hatcher and Elmer Keith. Both spoke favorably of the revolver for personal defense. Neither were especially thrilled with the "stopping power" of the .38 S&W cartridge, though both rated it much superior to the .380 ACP and both commented that it could be improved by hand loading with Keith's 160 grain semi-wadcutter bullet which was then (circa 1930) something new to the shooting world.
I have recently acquired a Safety Hammerless in what I believe to be the third variation and will post photos when it arrives.