I don't really believe in straw man tests with a Guardian. The overall damage is so low that you don't know what are errors in measurement or lucky hits and what has actual effects.
If Sustained Rage had a bug, it would only affect Guardians. Most Conquerors feat it and I never heard anything about a bug from their end.
I rather do some mumber crunching (that and watch closely what happens with my aggro in raids):
Sustained Rage:
I have a T4 pole and a T3 sword. The T4 pole has 153.5 DPS written on it. On the T3 sword there's 115.6 DPS. Sustained Rage 5/5 gives 15% weapon damage meaning 153.5 DPS*0.15 = 23.025 DPS for polearm damage in normal stance. For the T3 sword that means 115.6 DPS*0.15 = 17.34 DPS
Fortitude:
Fortitude 5/5 gives you half your amount of constitution as combat rating. At level 80 36.6 combat rating are 1 raw DPS. Atm I have 1173 constitution meaning I'm getting 586.5 CR, if every source of constitution is really counting (I'm not sure about AA sources). 586.5 CR/36.6 = 16.02 DPS. So, even if every source of constitution counts towards Fortitude, it's still way less than Sustained Rage.
Savage Strikes:
Savage Strikes 5/5 gives you 430 raw Combat Rating. Again, divided by 36.6 you get 11.75 DPS. Your sword must be really bad (green, not 80) if that's really better than what you get from Sustained Rage.