The human hand, and its' function is so variable that predicting ergonomics is fraught with danger. When my older children were outfitted with knives, I had a box full, and let them go through them, and check for ergonomics and ease of use.
What may fit one hand will probably not fit another.
I feel thumb stud knives, with the proper ergonomics for my hand, are as fast, if not faster than an automatic. Walt