Commando: His armor weighs 6.5 tons with standard armor. With Ferro you save a -huge- 12% of that weight, so you save 0.78 tons by having Ferro armor. It eats almost half your structure points. Hmm.
Atlas: Let's throw this big monster's armor even above what he has, let's say 640. This means his armor weighs 20 tons as standard armor, meaning that you save 2.4 tons with Ferro Armor, and again it eats almost half of your structure points. Endo-steel eats the same amount of structure points, however due to the weight difference in his potential structure (100 tons) and his armor, you gain far more tonnage for the same cost in structure points.
Endo-Steel's reduction is based off of the mechs potential structure, meaning potential max weight of the mech in question, which means that, across the board, the mathematics result in the same... Endo-steel will almost invariably result in near double the tons gained, for the same critical spaces.
Now, let us clear up the one, simple, myth that seems to surround Ferro armor. It... does...not...give...you...more...armor. Nor does it negate any more damage than standard armor. However you -do- have to pay for it's repair even if it gets scratched, unlike Endo-steel wherein you only pay if you lose a limb or take an unfortunate crit. Yes, it is worded funny, however if you actually read the specifics on how it is written, and test it out a bit, it will make a tad more sense.
The ultimate conclusion is that Ferro Armor is there for flash, and Endosteel is invariably worth more bang for your buck.
Sucks, I know.
Edited by Discordantone, 08 November 2012 - 07:21 AM.