In summary, it seems like the newer trend seems to be that people are using the thimble shackle captive screw pin like the Wichard #1495 ($69.99 at Defender) with a working load of 1500 kg. http://www.wichard.com/images/prestations/A-WICHARD-1495-0002.jpg
The Wichard #1494 is the same as #1495 but smaller with a working load of 1,000 kg is $44.99.

Alternatively, is the Wichard 81434 key pin with dbar for $45.99 but only has a working load of 800 kg. http://www.wichard.com/images/prestations/A-WICHARD-81434-0001.jpg

I guess after all this discussion, the #1495 shackle may be the most prudent one to use. I guess after all these year of using the key pin style that just flips open when you turn 180 degrees, I will need to get used to the newer style that you screw in.