Well, Pepsi, you know that you should get your gait professionally analysed blah blah, but it sounds like you are pretty neutral, maybe a mild pronator. You should go for neutral type (Asics Cumulus/Nimbus??/Saucony Jazz?) to mild stability (NB 734/Asics 1070/2070, half a million others). Unless, like me, you are a bit on the heavy side (actually I'm a fat git), stay away from motion control or very stable shoes.
Oh, and your last point, if it hasn't bothered you for 10 years, you can't have much wrong with your gait.