There's been a lot of dispute about this, and after noticing that the new GUI shows some augment damage buffs such as smite infusion with bonuses higher than +200%, I did some investigating.
First, thanks to Stefe for helping me test this.
The test was conducted with Smite infusion, with damage mods totaling to +156% power strength. This would make smite infusion grant a +320% bonus, over the proposed limit of +200%. (2.56*125%) The weapon was the classic Braton, without any mods. The enemies were level 10 Corpus Crewman, and level 10 Moa. Initial damage before augmenting showed that the Braton did 20 damage to a Moas health, and 22 damage to a Corpus Crewmans. After casting Smite infusion, this damage went to 100 against Moa health, and 84 against Crewman health. If the damage from the augment mod capped at +200%, against the Moa, we should be doing 20+((20*2)*1.25); 20 base damage, plus two times that as radiation, which has a +25% modifier against robotics. This comes out to 70. Funnily enough, 20+((20*3.2)*1.25) comes out to 100, the damage numbers we were seeing. Even against the crewman, 20 base damage, plus an additional 200% (+40 damage,) should total to 60, but we saw 84, which is 20 base damage plus 320% (64 damage.) Since the math is conclusive against enemies with and without resistances. I think its fair to say that the myth that augment mods can only go up to 200%, is busted.
While Mirage can reach 568% damage with Total Eclipse, this is only in perfect lighting, a max damage Oberon can get +355% radiation damage, which against an Elite Lancers armor where it has a 75% bonus, will mean you deal an additional 621.125% damage against Draco's most common enemy.
So for all you rep farmers out there wanting to get the best; Saryn = Oberon > Mirage > Rhino ?