For me, the finger assisted opener is very reliable and very fast. Although I have never thought of that knife as a piece of "tactical" gear, if 1/3 of a second made the difference between life and death, I'm thinking I must have messed up somewhere else.
Defensively, the knife is a reactionary, close range tool: you always want to use something else if you have the option, and it will always be used at close range. With that in mind, yeah, an instant can be a big difference at contact distance.
John