Sounds like I'm in the minority, but I use an adapter quite a bit on my G6. I tend towards outdoor photography, and I often use a polarizer. However, I use my camera often enough without add-ons that I don't actually store my camera with the adapter mounted. I did find that bags that were small enough for the camera alone weren't as comfortable as wider bags that had room for the adapter and filters. The added weight is minimal, but the wider bag is much more stable against my torso. I found the little bag swung and slid around, banging into my arms while walking, etc. I think the small bag is much more like a cylinder, so it's very easy for it to "roll" against me, where the wide bag just hugs where it sits, and I can almost forget about it.
That could all be just the bag I had--go to a LCS with a wide variety of bags, and try your G1 without accesories in them--it should be a good substitution for a bare G6. Walk around. Bend over and tie your shoes. Does the bag slide around and smack into the floor? That's bad. Adding a belt strap to the shoulder strap would prevent this, but I found that cumbersome--try it though, might work for you!