I owned a number of assisted knives, including a Leek, all with thumb studs. I decided that they were not an advantage for opening the knife because I had to get my thumb precisely on the studs to open it, and even then I could occasionally slip off of the thumb stud. The only exception to this was the Kershaw Blur that has a large and sharp thumb stud. I found that the large blade hole that Spyderco uses is both quicker and more positive for opening, so those have replaced all of my assisted opening knives.