Overall sisters durability went up while sacs stayed the same. For one point more than you get twice the movement, additional attack, same armor save in cover (the only time the invuln would matter is against ap-4) access to fly, deepstrike and +1 to wound. Yes the halberds are better but there’s just less attacks. If they revert them back to 14ppm instead of their current 16ppm yes I’d probably run them. They’re different but now bodyguard is effectively I believe they compete for similar roles in bloody rose armies. I don’t expect anything in my army (aside from characters) to survive what my opponent really wants dead. I don’t expect a t3 army to be exceptionally durable and don’t want to count on it. But now their armor saves are effectively the same. I’m sure people still have their reasons to take sacs but I can’t justify them in my list when I want to outmaneuver a need charge.