I never got to experience Master Kuo's skill first hand (some would say I am lucky), but I did meet some of his older students in Taipei and later in the U.S. One of them, Yang Zhifang (Chihfang Yang) had a studio on East Broadway in Chinatown N.Y. in the early 1980's. I went to visit - Mr. yang was shorter than me and slightly built, but wiry and muscular. He must have been in his 50's at the time. I was very impressed by how he moved - and all of his techniques had a quality that the Chinese call "hen" - something I associate with very good Shaolin and Tongbei. Its a quality at the end of a movement as if striking through with intent to do damage (the physical end of "take that!"), like throwing a knife into hard ground. His Taiji and Bagua were very quick and crisp, and they did a version of Tantui that was just a pleasure to watch - quick, powerful, solid. They started beginners with a version of Ba Duanjin that was very effective at building basic body posture and movement - all in all very impressive. What impressed me too was that the quality of teaching took root in his students - I saw several, and they all had good foundations and movement, and knew what they were doing. This was the first American school I had been in where the Taiji students had real martial skills - they could use the techniques of the system (rather than kick box).
Not a year after the school had opened, it was closed by a suspicious fire - apparently Master Yang was not wanted by some members of the "community" (I suspect he refused to pay protection, which was rampant at that time).