Am i understand correctly that kill of the hill will work in next way?
When city is taken, then small gear check is made (as described in first post). And if these people stayed in city, then other gang should have better equipped team to retake (or basically killed previous gang defenders).
If defending gang left, then only initial gear check should be .
E.g. if 5 people in metal take city, 1 left, and 4 stay somewhere, then gang that want to retake, should have at least 4 people in metal. Or they could kill those 4, and retake city with default gear.
This way defending team could choose location where to defend.