first, i think the best is not to let ones leg get grabbed at all. so one would need to do a sprawl-like motion while not really holding the guy too much or leaning on him..just evasion. secondly, i think the most effective way to respond is with a strike- as in a kneestrike(keeping balance!) or elbow or punch...even to the back of the head if necessary. next best is the clothshanger or guilitine choke. or swing around and apply some other kind of choke- shooting does leave you open. if one cannot be fast enough to take the balance of the other, shooting is risky- however if done correctly, the risk can be minimized. -i personally don't like shooting because i feel it leaves me too open. but for ever techinique there is a right application.
the shooter is expecting contact, so one way would be to get really close and give the illusion of making contact and then step away-maybe hold neck and push down or strike from there- depends also on the strength and stability of the opponent.
only thing that could go wrong with that is that you get too close and the shooter get a hold-in which case, you may already have forfeited your security.
there is one supercool move that i worked on for a while. that is, when the opponent shoots in, you stand strong while applying a guilotine choke, your other hand simply grabs the opponents wrist on the same side as own grabbing arm-like one would ride a bike. then, one puts ones own head under the arm/armpit of the opponent-(warning: this leaves extremely vulnerabel because if opponent clamps down his arm, he squeezes your head like a zit basically also guilotinestyle but inside of biceps/armpit)
so, the way that i improved this was to force the opponents arm down-in effect pushing him forcefully in the direction of own head. thing is though, that high chances are, he will resist and that will make the move work perfectly. also, it might be better not to wedge owns head under the armpit in the first place but rather just lower owns head sortof...
the move is like this, once one has the choke with one hand and the other hand holding the wrist, own head is lowered(like own back of head is on front of opponent shoulder-best)
own front leg is same side as the choking hand. without letting go of either grip. both wristhold and choke, you start to turn in the direction of the back leg. if choking with right arm, that is clockwise.
keep turning untill the opponent is behind you with his neck bent back in a nasty way..you can stay there or keep turning which is really disorienting for the opponent,and drop him -the disorientation and superior position gives you considerably sufficient time to apply another move. if this move is done forcefully, it can break the neck in one move. so go easy.
trick is to push down at the start and when the resistance is there, you just absorb the force and turn. ive made this work a number of times.
if you hold on tight to the choking arm, it's almost too hardcore to even perform safely.
j