So if I understand correctly, the Battlesuit can be obtained at level 4 Purity:
Battlesuit
Moves: 2; Strength: 40 (up to 66 with upgrades); Cost: 160 production; Requires Resource: 1 Titanium
To get to this unit requires:
Three ring one techs and one leaf: Engineering, Physics and Genetics (Genetic Mapping)
One ring two tech and one leaf: Bionics (Servo Machinery)
A Purity quest.
Compare this with the level 4 Harmony unit:
Xeno Swarm
Move: 2; Strength: 34 (up to 60 with upgrades); Cost: 120 production; Requires Resource: 1 Xenomass
To get to this unit requires:
One ring one tech and one leaf: Ecology (Alien Biology)
One ring two tech and one leaf: Alien Sciences (Alien Adaptation)
A Harmony quest.
Compared to the Purity Battlesuit, the Xeno Swarm has -6 Str, but costs 40 less production and requires two less ring one tech expenditures.
Opinion: This seems like a fair trade to me. For every 3 Purity Battlesuits (120 STR), a Harmony player can have 4 Xeno Swarms (136 STR).
As for the Supremacy level 4 unit:
CNDR
Move: 2; Strength: 38 (up to 72 with upgrades); Cost: 155 production; Requires Resource: 1 Firaxite
To get to this unit requires:
One ring one tech and one leaf: Engineering (Power systems)
One ring two tech and one leaf: Robotics (Tactical Robotics)
A Supremacy quest.
Compared to Purity Battlesuit, the CNDR has -2 Str initially, but becomes +6 Str better than the Battlesuit with upgrades. It costs 5 less production and requires two less ring one tech expenditures.
Opinion: This seems like another wash. Sure the CNDR sacrifices initial STR, but as the unit upgrades its STR outstrips the Battlesuit.
Final thoughts: I find it very interesting that Purity level 4 takes longer than the other two affinities. It requires six techs and a quest, whereas the other affinities can grab their level 4 units with four techs and a quest. perhaps Firaxis took into account that the Purity line leads to Bionics and more research whereas the others don't lead to more research. Anyway, as long as these numbers from Civ V Analyst are correct, then I think things are relatively balanced for MP with Supremacy being the weakest initial choice, but much better once it upgrades the CNDR.