In your comments on Position 4, you write "But at the end, W's main group is sealed in anyhow while an eyeless W component is cut off in the central region and under severe attack, to W's great profit from every attacking direction. And when the attack finally peters out, W takes sente to play at y anyhow.". Shouldn't it be "[...] to B's great profit from every attacking direction. And when the attack finally peters out, B takes sente to play at y anyhow."? (When this is resolved, you could delete this comment.)