I don't know how long this has been out there, but I just found out and for me this is HUGE!

Ortlieb has brought out a quick release handlebar bag mount that fits all of the ortlieb ultimate bags. Here's the link https://www.ortlieb.com/en_us/handlebar-mounting-set-qr

This uses a same system as the QR handlebar bag but this is just a mount.

Let's face it, the cable mounting bracket has always been a bit of a faff in every regard. It's super sturdy yes, but once it's on, it rarely comes off again. The cables aren't all that multi use so after a few assemblies and disassemblies you'd usually need a new cable. And the mount + bag makes using handlebar mounted lights impossible and using garmin units etc. difficult.

This new quick release mount doesn't fix everything but it gives the option of taking the mount off on a whim and using something else or nothing at all. For my road bike I don't generally like using an ultimate bag. However I need some sort of handlebar bag most times, so I use a small cylinder bag for shorter rides. For centuries and longer I still need the ultimate. As you can imagine, this need for the ultimate bag has complicated things in the past. But no more!

The QR system is quick only relative to the cable mount but it doesn't take many minutes to install and under a minute to take off. It's pretty nifty and surprisingly sturdy.

Still can't use it on carbon though.

Someone with intimate knowledge of the products mentor me: Ortlieb and Carradice handlebar bags fit the Rixen/Kaul KlickFix mounts, no?

I ain't no mentor or expert, but the Ortlieb Ultimate Six bag, seen here mounted in the seatpost via a KlickFix caddy, fit perfectly.

it depends. They fit some klickfix mounts, but there's a lot of different models

Pardon me, but isn't there a single, standard KlickFix mount?

Sure seems that way. Mind you, this apparently hasn't always been the case. We have at least one klickfix basket that doesn't fit ortlieb mounting brackets. It has this different slidey thing...