Bikepacking - a viable alternative to racks & panniers

The Rixen & Kaul system are a tried and test system that will be reliable.

The main problem is the weight, it is 1026g just for the system alone, this mean you're effectively paying for the ability to take it out in second, 1026g is an awful lots just to have that ability.

A similar system that doesn't have a quick release but can easily be mounted using the dry bag is the Specialized Burra Burra handlebar system that weight only 318g for comparison, the hardware need to be properly mounted on the handlebar, but once it's mounted, there's zero slack and play whatsoever;

PDW Gear Belly...

You're gonna have to think about the trade off between ease of use and weight.
You'll quickly notice 1026g when steering the bicycle before you pack it up properly, a good handlebar bag may not be easy to strap on/off* but the big advantage is that you'll save nearly 1kg in weight alone that can be added back when you pack it.

What I don't get with the PDW bag is that it design to be removable whenever you want with the R&K system but it also design to make it easy to remove the dry bag from the system without taking it off the bike, so what the point of having a removable mount that add weight only to leave it on the bike when mounting the dry bag onto the system?

The Apidura Backcountry Pack in the largest 11L capacity is 270g (and can fit drop bar bike providing you don't overfill it).