So, while this is a totally unscientific statement with respect to damaging a knife by opening it in a more violent/faster method than another.
HOWEVER
I will say this. IF you carry a blade for defense, you better be TRYING to destroy it by drawing and opening it in your spare time. Muscle memory makes fast and accurate. Not slow controlled openings, not a particular technique (so long as your technique involves the fewest and shortest movements to achieve a task), flicking, buttons, springs, assists, what have you.
So long as you have a quality folder that is properly maintained, you should be able to achieve about the same speed of deployment. HOWEVER, if you think you can baby your baby and at the same time get good at deploying it in a defensive situation.............you are gunna be the one who gets bitten. Practice like you mean it, or don't bother.
That being said, choose a method that feels most natural to you. Then do it 50 times a day, refine the movement each time. That will produce results you can put to work.
As better (but more expensive) alternative, I would suggest picking up spyderco's trainer that suits you the best. That way you won't be beating on your sharp knives, and you won't risk cutting yourself.