This is what I use all the time. The advantage is, that I get the GR even with the case into a bigger pocket. But mostly I have it within the case in my hand or on my belt. Cheap ebay China stuff. No real leather I think.
I would not recommend to put any kind of camera in a pocket without a camera protection. There is so much dust etc. in a pocket that you will harm the camera sooner or later. No matter which brand. No matter which pocket.
It is the same like taking a camera to the beach without camera protection. Even the slightest wind will put really fine sand into your camera, which you can not see, but feel.
I always carry my GRs with a leathercase. As small as the camera. See another thread about accessories for this. I never had dust issues or other issues.
I got a small edc dyneemabag from a german guy on etsy.(ultralightbags or such?), fits the gr's just fine, even with the filterattachment and a spare battery. Works winter and summer everywhere.
The new version has properties that i do value and depending on the price, I'll most likely switch it later in the fall when it has arrived to stores.
You're right about the threat of dust. I used to have a GC-11 leather case, but it was just too big to fit in a pants pocket, even though it's only a few millimeters larger than the camera itself, and makes the camera that much slower to deploy, so I often just risk it. But it's a fair point and a much more careful approach to use a case. I'll have to look into the Dyneema bag, which at least solves the size issue.
Either way, though, it's well documented that the rocker switch and rotary dial can have issues, so I'm glad to see that the GR IV prototype design appears to abandon them in favor or something that is hopefully more reliable.