Don't get me wrong, the Escalator is probably as well designed for this purpose as you will find, it's just that I don't think the theory behind it is really as practical as it sounds.
Were I in a situation as described above, I would be better served to grab the guy's wrist with my left hand, uppercut him with my right, and then sweep him with my right leg while my left maintains control of his right hand(assuming he's a righty) and help push him over with my right hand grasping his throat.
Now that he's on the ground, still latched on his throat I can beat his head against the pavement until he ceases and desists.
If I had drawn my knife before he'd drawn his gun, I would drop it in favor of the above, or open it and drive the point into his chest cavity and wiggle it around in lieu of the uppercut.
Sure, a hard smack to his wrist might make him drop the gun, but then what? I'd rather just take control from the begining of the engagement.
Sure, you could try the same thing with the folder, but I have serious doubts about it being more effective. I think it is an intresting concept, and makes sense from the standpoint that we all like knives more than is reasonable and therefore want to make one perform things that they really aren't cut out for(but that's another topic), but as to actual practical application, I fail to see it offering a decided advantage.
I supose you could always say that I'd have to be highly trained in the Kyushu Jitsu, but then again I've been in my fair share of scraps and have seen a number of different fighting styles. I've got a fair idea of what offers a decided edge and what doesn't.
I guess the main thing that this has going for it is that after you've used it in a way similar to what I've described above to subdue your opponent you can then open it and stab him to death. But there might be legal problems with that, and it's nothing you couldn't have done had you left your folder in your pocket during the initial stages of the fight.
In all honesty, these little(4 inch and under) folders that are popular these days just don't see much action until towards the end of the fight or unless things are going real bad for you, simply because unless you're the one on the offensive you don't neccesarily have time to produce the knife as you're too buisy defending yourself with unarmed techniques.
The other situation is that you see the fight coming and have plenty of time to draw and open.
This is an intresting concept knife, but in the final cut it just looks a lot more like a curio than something that really offers you an edge.
I'm all for more options, they're a good thing, as long as those options are relevant. More just for the sake of having more isn't neccesarily better. I mean, a thermometer built into an axe handle doesn't really make it a better axe, and you can usualy tell wether it's hot or cold outside with your own senses anyway.