I have been practicing this type of opening for a long time now. I first learned about it on Mike Janich's tape on fighting folders.
However, I have to say that I have abandoned it in terms of a practical means of opening a knife in preperation for combat.
The problem is in fine motor control. You have to have a firm grasp of the knife as well as a flexible wrist. If you have both tight, you can not generate the torque. If you are not strong enough on the blade, it goes flying.
The thing is, under the stress of adrenaline, fine motor skills like this are the first things to go flying out the window, probably followed by your knife.
I have spent countless hours while watching tv opening a drone version of the Spyderco I carry. Yet, when I tried it a little typsy, I could not pull it off. The same went for trying it after I had done enough push ups to make my arms want to fall off. I was able to pull it off when my arms were ready to freeze in winter. However, my tests show that with even just a little loss of motor control, the skills were just no doable. I expect my motor skills to be even worse should some thug corner me and announce his intention to kill me.
I think I am going to reccomend against practicing and relying on this until I hear a story of someone able to pull it off under a real situation and not just the training I have gone through.
Anyone know of any cases? There has got to be something out there on the subject. Or is this just not well known enough for someone to have been able to try it in combat?