So which bogs were ok and which was bad? I cut the corner on the way to 11, ran around the rest.
I skimmed the corner to 5, no problem. That made me confident to try cutting to 8, big mistake. The liquid area extended further than first visible, and the grass tufts disappeared half-way across. That's where I sank in pretty deep. Still had a ways to go. To 11, I cut R, which was okay, and did the same to 12.
Overshot 10 to the boulder about 100 m past, relocated and flipped back. Not a clean area.
Agree with your assessment of marsh on way to 8, and I also was influenced by easy crossing of marsh on way to 5.
I'm assuming you went through the right part of the marsh on the way to 5. What I could see as I went to the left didn't look very appealing.
Actually, going to 5, I planned to go R, but when I got to the edge it proved to be runnable, so I went straight across.