It's not "easy" because it moves around quite easily, it's a coordinate hands on activity to draw. But it works for me, there are times where I have to quickly remove it and stuff it in my pack.I second @G4Y4HK 's question, how easy is the Patagonia Atom to draw with?
The Helicon-Tex Sling Bag is a dedicated EDC bag and can accept various holster attachments. I don't think the Patagonia will have this functionality.
A better solution is something like the Hill People chest bags which are fixed in place. This would be great if you are doing fair weather hiking/walking.
Hill People Gear | Real use gear for backcountry travelers
Some winter/glacier routes I just have too much other stuff to manage, 3-4 layers and this isn't a great idea.
Sir, I only wear fanny packs when I'm riding my bicycle.an old good fanny pack is now called a 'sling purse'? go figure, progress...
I don't carry when I'm at the gym working out, sometimes you have live on the edge. I don't even lug around a giant gym bag full of useless workout gimmicks, never mind a firearm. Just lift heavy and go home, you'll be fine. Are you guys strapped on the mat during jj class too? Haha.