Your getting faster Mook! Master Fung was scary fast!
The speed of your punch will increase the power of your punch. Mass x Speed = power
And yes, make sure to go back to your chest. More power and helps to keep you from getting latched.
As far as Wing Chun is concerned , assuming our stance is developed , speed is the main contributor to the equation .
If your stance is ok and you have learned the correct way to coordinate your punch with stepping , then a very large percentage of your body mass will be behind the strike.
Unlike an automatic weapon where you can change the ammunition , we can't suddenly start decreasing or increasing our mass.
Not without spending a fair bit of time dining at the " Golden Arches Restaurant " or putting in some quality time at the pub that is.
You can increase your muscle mass by heavy weight training , but in Wing Chun that can be counter productive.
So that leaves us with increasing our speed , this is done by increasing our level of relaxation through practice of the Sil Lum Tao form , Chi Sau and punching drills etc.
Either you did a lot of talking without saying anything or I'm not understanding your rebutal towards my theory.
I thought the "better to be thin" in martial arts was debunked decades ago after seeing huge guys in the UFC that also trained in the arts to become even more potent than a skinny guy with a little more speed.
And my wing chung coworker who is working on becoming an instructor in the next year does the hip thrust punch as you explained and it was more like a push and looked very innefective and useless in a real fight.
The problem about what your saying is that short punches can be powerfull given time in training. Ok fine, but longer chambered punches which WC is against due to them being telegraphed, will always be that much more powerfull given the same amount of training.
It's like the no replacement for displacement phrase thrown around in the car racing community. A 4 cylinder can easily beat a V8 but given the same time and money in the V8 it will always be ahead "potential wise"