At this point, I could not live without Fences. However, I've always had an issue with it that never seems to get resolved. Perhaps it's because I have a high DPI laptop display?
In any case - I keep my fences "rolled up" - so each fence has a different height when unrolled....so when I try to drag the fences and line them up (when rolled up), sometimes they "snap" where they should, and sometimes you just can't get the fence to snap where it should.
Snapping just doesn't seem to work when they are rolled up. I've tried to play with the few settings for snapping and layout, but still have the same problem.