Hi, Numanoid, Too late this time but,I had this idea (ideas are cheap) that one day the entire backbone would be splined into 40 sections or so like a human backbone. Same zones; head, neck, chest, abdomen and hip for treaking but all could be controled from the hip. X rot or "bend aft" would give you a decent arch for a sitting pose. Or, twist aft, or side to side aft...No IK required. Since we are in ideamode, perhaps a lot more (3x) mesh in the hip altogether as this is a weak point in v3 and others. Maybe a new clever set of zones to avoid distortions. Good luck on your model.