If I may offer some All noise Fcukall Insight to this discussion, regarding hydraulics needed for control of rotor systems ...
A fully articulated head on a 12,800 and a 13,500 lb pound helicopter can be flown without hydraulics (it is easier with, and the tail's a bit of a pain wihtout hydraulic boost) for extended periods by using the Kaman Servo Flap (SH-2F and SH-2G) style of blade design. The down side to that design choice is more parts, and the attendant increased maintenance and change of dynamicly loaded parts 12,800 lb with greater frequency. (Pitch change rods, flap attachment hardware, etcetera ... ). Based on the pictures, it looks like they did the same in the K-Max. Have not flown that (12,000 max GW IIRC).
From memory, those blades are not symmetrical, but I may be misunderstanding how that is being used in this conversation.