What's the advantage to using threaded cornelius keg disconnect fittings and barbed swivel nuts over barbed disconnect fittings?

The quick disconnects with 1/4" barbed fittings are pretty straight forward. You connect them to your liquid or gas tubing by clamping them down with an ear (5183, 5184, 5179) or SS tubing clamp (5182). If you're working with 3/16" liquid tubing, it will be helpful to dip the end of the tubing in hot water to fit the tubing onto the barb more easily.

There are a couple reasons you may opt for threaded disconnect fittings. If you go with a threaded gas fitting, you can get a better fit onto the 5/16" gas tubing by using a 5/16" barbed swivel nut (5187). Also, the threaded gas quick disconnect will screw into the compact CO2 injector (5110C).

Using liquid threaded quick disconnects with liquid tubing outfitted with 1/4" barbed swivel nuts allow some increased functionality like constructing a keg to keg "jumper cable" for transferring cleaner, sanitizer, or beer between kegs, pushing with CO2. Threaded disconnects are also useful for switching beer and gas serving lines around to counterpressure bottle fillers ( 5325, 5327F) or creating a compact chrome faucet along with parts 5113 and 5360. As you can see, the threaded connectors allow for all sorts of extra functions and possibilities for your kegging system!