I've done SP twice, both times without the crux hook placement, and found it to be C2. It is most definitely not A3. You are never more than one piece away from a bomber placement. There's a line left of Kansas City that crosses Outer Space Direct on small seams and right facing corners. That felt harder as there were multiple tenuous small wires in a row above an ankle breaking ledge, followed by two consecutive hook moves. That felt C2+ to me.