I’m not sure if you know which kind of bong I mean. Are you talking about a bong off of a straight punch? The movement I’m talking about is off of a round house punch, and you do a RIGHT bong sao for a RIGHT punch, but you bring your left hand up towards your face, and if your opponent was aiming at your head the blow should land in between both of your wrists. After that the bong sao hand slips underneath your opponents arm and either pins the elbow, or pulls the opponents arm down. At the end of the technique you should fine yourself on the outside of your opponents RIGHT arm (if he through a right punch) with the left arm out of reach. Obviously this move has to be done with proper stepping aswell, especially since the second punch may be right around the corner, and you have to step in a way as to evade that punch and move the first punch in a way as to not slam it right into your face…
I’ve been doing TWC since 1989 with Rick Spain. I got gold sash in 1995 while we were still aligned with the WWCKFA.
Moving from inside to outside after blocking a round swinging punch in the way you describe is pretty impractical. There is a weak spot moving from the bon through tan as you move the punch past, during which you can get nailed. Also with bon you are usually too close to allow the punch to go past anyway. If you want to “pass” the swinging punch from inside to outside, the bil sao/tseun sao is a better option, though you will probably still need to step backward to do it. The problem with both of these techniques is they require you to stay in a place far enough away for the punch to pass by, but close enough to retaliate. You are still too close to the impact zone, generally the safest place to be with a haymaker or hook punch (other than in another suburb) is well inside the arc.
I also doubt the efficacy of these movements against a nice tight boxer’s hook, which I’d try to weave under or take on the forearms/elbows with a “brush the hair” block, rather than seek a longer bridge.
There APPEARS to be a move in the TWC dummy sets 1&2 that has the application that you describe, but in my Sifu’s and my opinion the application you describe of it is not viable. A better application is using the bon to stop one strike, and then the tan off it to block a second strike, NOT move around the same arm. Or backhand him in the face or poke him in the elye with the tan from the inside.
Against the sort of punch you describe, I might use a bon, but stay inside - after all I may not have the luxury of choice. You can still zone away from the other hand on the inside while you hit him in the face with a side palm, elbow forearm or whatever. You have to deal with his other arm, but from here you have a reasonable amount of contact with his initial punching arm and can control it, so you are still really only dealing with one arm. Then just beat the crap out of him from this position.
We normally start people sparring in a light, controlled fashion at around the same time we start teaching 'em chi sao. Opinions vary, do what your instructor recommends. I haven’t noticed it causing anyone a technical problem.
Martial skill is the least important aspect of self defense. Read “Strong on Defense” by Sanford Strong if you want to understand the more important aspects, or check out the link on “surviving violent crime” in my .sig.
I take multiple MA’s too … can be confusing, but it’s fun.