I have no idea how much other armors enhance the user's strength. Considering most factions have super soldiers with super strength already enhanced.
But to explain it better the armor assists the user through servo motors and other mechanical means. It is like a small Exo. I also did some looking up on the performance statistics of already existing machines, and going "real" would have pushed the envelope. Icly, remember the goal of the upgrade was to grant the user better protection, and strength, while maintaining the agility of the soldier and minimizing the need for operation training. The Gartagens also do not have super soldiers, they have this.
Secondly to add balance this upgrade does not "Have it all." The armor enables the user to use larger weapons(I am going to do the justice of saying that they can handle ADR 3 weapons and lower.)
It has gives the user an armor value of ADR three making it smaller, and not nearly as robust as other power armors.