Russ,

If you don't want to put too many keys on it, I use a Ti and Brass screw link from CountyComm http://www.countycomm.com/tiscrewlink.html
I have several and all but one lock very securly. They are much smaller than what you have discussed but will carry a fairly large load. One carries my personal keys (3 house keys on one ring, 2 car keys on separate rings, a mini pry bar and tube whistle on another and Fenix ML flashlight on a clip. My school keys include 3 keys on one ring and a key, mini screwdriver, pry bar and another key on a separate ring and a Streamlight 3N. I carry my keys with the light tucked into my waistband and the keys on the outside. A true carabiner is uncomfortably large (needs to fit at least a rope and a sling or two) and I don't like the mini's.

Just a customer.

Respectfully,

Jerry