I am no expert, so I am only responding to what I heard from a few extensive conversations with my friends from Taiwan. I have been thinking about this for a long time, ever since Kuo and Chang told me about this two years ago. I have also talked to some pinoy players such as Ronnie Alcano about this. I will try to explain here what I heard.
From what I observe, Taiwanese players all have a very good understanding of body machanics. The game is taught very scientifically, and systematically in Taiwan. Pros are also quite willing to share their "secret" with others for free. So, they have improved a lot in recent years. This also explains, in my opinion, why they might all believe in similiar theory and use a similiar system when it comes to shaft preference, adjument for english, and such. Therefore, we need to bear in mind that just because they all believe in a certain thing, does not mean they have all tried different things before they settle on the one thing.
What Kuo told me was that (this is what I understood, from what he tried to tell me, but I cannot be sure I have understood it completely) the ball will always swerve at slow and medium speed. He said that with a smooth cueing action, not too much adjustment is necessary with most cues. Good players never hit the ball too hard, and the cue ball usually will throw the object ball a bit and swerve a bit, so just because a shaft has little deflection does not make it go straight, if you hit it smoothly. When he said that, I looked at him, and I remember he was using a Tad in the WPC finals against Wu in 2005, and Tad has one of the most "deflection" of all the cues I have tried--so, I was having problem believing him.
He saw the look on my face, he asked me to stand behind him, and he showed me. He told me he usually tried to be very precise with the point which he aimed to hit on the cue ball, and he would follow through very precisely. Not too much english is needed to make the ball spin a lot. He also said he would use swerve to adjust for initial squirt. He told me he never really hit the ball real hard, especially when he really wanted to move the cue ball around the table--only lots of smooth follow through. I asked him how he got a smooth follow through, he told me he allowed the weight of his arm and his cue to creat the follow through.
When I stood behind him, I noticed that he only made very little adjustment when applying tones of english on the cue ball by hitting only a tip away from the center, and he hit the ball real soft yet smoothly. He made a 4 rail shot effortlessly. It was amazing.
He told me not all cues would allow him to move the ball around this way, and a "powerful" cue is one which allows the cue ball to move around effortlessly, whereas he can just let the cue do the work.
But he also told me since they play on very small pockets in Taiwan, they do not usually use too much english. It is very important to learn to control the cue ball, so they can have a good angle to move on to the next ball. He said when he was playing well, he could control most shots to land in the size of his fist. He also told me that they have many ways to stroke a ball, depending on the shots. They learn to strike the ball with many different strokes, for many different shots. Most people are taught to stroke the ball one way, and to use one stroke--but that is not what he believes, he actually believes in the opposite--the more stroke you know and are able to execute, the better you are.
He has a lot of respect for the US players. When we were in Q Master, he watched Scott Frost and he was really impressed by his stroke. He asked me why such a good player never comes to play in athe big international tournaments, such as the World Championship. He said Scott hit the ball real pure and has very nice follow through.
He also agrees that a pro taper is more forgiving, but he said it is not "stable", and is not as "consistent." I was not too sure what he meant, so I have talked to lots of people and tried many cues such as Southwest.
From what I understand, they are looking for a cue which can give them exactly what they expect to get everytime, so it is not just about moving the cue ball around the table going 5 rails, but more importantly, it is about the shots when they need to control the ball to draw back say only 3mm. In other words, they want a shaft which allows them to control the cue ball accurately and consistently, whereas most people are looking for a shaft which allows them to aim accurately. I think this is the biggest difference.
About "power," I think the best way to explain it is to try out the break out shot in straight pool. A Southwest shaft, I have seen, in the hand of a good player from Taiwan, will pound the cue ball throught the balls, and left the balls scattered all over the place. With a less powerful shaft, the cue ball will get buried in the pack. You can also see this "power" in snooker, when the cue ball goes through the pack, and seems to have a turbo on its own, pounding through the pack, going left and right. It is not achieved by hitting the ball real hard.
I do not believe they believe the stiffer the shaft, the more powerful it is. I think it is a certain taper, and balance, that they prefer.
I know 314 is very popular among UK, USA, and Canadian players. It is also gaining a lot of popularity in China. I can see why snooker players would really appreciate the 314 technology, because it allows them to simplify the stroke and aiming.
I have seen and tried Ronnie Alcano's shaft. It is a very slim and long taper, one piece, regular shaft, with a soft tip, like a le pro or something like that. He also hits the ball very smoothly, with hardly any effort. Ronnie Alcano admires Efren Reyes. I suspect he models his stroke after Efren's.
Personally, I believe there are many ways to achieve excellence. And there are many shafts for many different folks with many different strokes.
I am sure the 314 is the perfect shaft for some folks. Corey Deuel can do magic with his 314, and look at the cue power of Jasmin Osuchan!
In response to the questions about Taiwanese, I could only speak from my own experience, and what I was told. I am not a good player, and my understanding is therefore limited by my knowledge.
I hope this helps.
Richard