Don't forget time-travel undo. If you get into a weird state with the undo tree, and g+/g- aren't helping, you can do ":earlier 5m" to go back to where you were 5 minutes ago, and ":later 30s" to step forward.
Unfortunately, when you're at "now" you can't do ":later 30m" to see the future.
Unfortunately, when you're at "now" you can't do ":later 30m" to see the future.