It probably goes without saying that good judgement is the best self-rescue... but thats a cop-out answer.
My self rescue... humm while I'm fairly confident in it, and have practiced many times in a wide range of situations (flat, wind waves, swell, tidal currents, surf) both by myself, and doing assisted rescue practice with friends, plus rescuing indviduals in real situations (generally the 'Opps' I forgot how to stay upright type of rescue) I know that twere I to actually be in a situation that put me in the water I would be scared.
I have not capsisized unintentionally (except while playing in surf) for the last 600 paddling days (knock wood)... however, does not mean it will never happen. When that day comes, and it is a 'when' not an 'if', all one can do is have practiced as much as possible ahead of time in many different situations.
It only takes one variable to mess up that practiced and perfect rescue... you go for a roll but try and do it into the mushy lip of a wave, or hit a rock. You come out of your boat and lose you paddle. You are unable to get your spray skirt back on while you pump and therefore unable to pump as water continuasly reenters the boat.
As for the roll, I'll concure with others that it is more a maneuver rather than a rescue. However, if you are rough waters, you will be using almost all you paddling techniques, and thats okay... but if your using your roll in rough conditions as a maneuver, probably a sign you are in over your head.