Since I've begun studying Xingyiquan I've noticed some profound changes in myself. Increased stability and a stronger structure are the most pronounced. The first month I tried to learn the Wuxingquan (and Wuhuapao) as fast as I could, when I had time to train for four hours every day. I soon became frustrated, though, and realised that, although I was seeing progress, I wasn't making efficient use of my time. Furthermore, I ended up not liking the forms as much as I initially thought and felt that I have already learned most of the techniques that I liked from other arts.
So, for the second month I have concentrated entirely on Piquan (which includes Zuanquan) with a little bit of Wuhuapao, solo and with a partner when available. Now, I have found that I'm improving much faster than before and I've even decided to not learn much else beyond this and just add Piquan Zhuang (doing Zuanquan and Piquan line drills very slowly) to the core of my system. I also had time last month to put everything that I learned from my previous master together into a very short, two-minute form. What I really needed was to improve my structure and footwork and get a little more Zhijin (straight power) and it's starting to pay off.
So, why Piquan Zhuang over Santishi? Firstly, due to an old foot injury it's very uncomfortable to stand in one position that long. Secondly, it's boring as fuck. I have patience to do a lot of things like hanging off of a cliff for hours photographing a tree frog or getting up at four to do line drills over and over and over, but standing is not one of them! Also, when doing Piquan slowly I'm doing Santishi over and over, with the footwork that I'd actually use in a fight. One of the reasons that I quit doing Taijiquan was because the system lacks efficiency. Xinyiliuhequan, Xingyiquan, Baguazhang etc. get to the point quite fast. Since I studied a combination of those systems and others it's taken some time to put together a cohesive curriculum.
It doesn't make sense for me to dedicate large portions of time to standing (or Chansijin for that matter). Training Piquanzhuang I am training my structure, my root, my footwork and later, after I gradually increase the speed, my Fajin. I have my own version of Zhanzhuang in which only the upper body moves, a little bit like Chansijin but in a fairly high stance and directly applicable to combat (after adding footwork). Piquan Zhuang is a perfect addition to my (and anyone's) system. I think that it's really the core of the art, which is why it's called its Muquan (mother fist). Doing a half an hour of it goes by really fast and the benefits become obvious very soon. The rest of the art can be substituted with pretty much any other art and it wouldn't matter much.
I'm going to spend most of my time with Wu Shifu making fucking sure that I master Piquan (and by inclusion, Zuanquan). The other three I have learned in other arts already... In about four months I plan to begin visiting the local Sanda schools at least once per week and putting everything that I've learned to the test until I leave China at the end of next year..