I was thinking about readied actions today, and it occurred to me that you can ready Total Defense as an action. It's a standard action, and you can ready any standard action.
If you ready Total Defense as an action in response to any attack, you get the full benefits of Total Defense AND you still threaten until you are attacked.
Seems that if you are thinking about going Total Defense, you should always do it as a readied action. Only downside I can think of is that it would possibly change your initiative, which you may or may not want.
If there was a situation where the DM rules you couldn't react to the attack (maybe flat footed vs. an invisible attacker), then the dodge bonus wouldn't have likely applied anyway.
Is there anything I overlooked?