Great thread and all round great input.
First off, I found the assumption that masters don't befriend each other and exchange material quite unsettling. I think if we look closely we can see that a lot of masters learn form each other especially when they have equally quality material bring to the table. A lot of people went from other styles to learn Mantis. This doesn't mean that they will have to be brainwashed and forget about what they already achieved.
Second, the following is my very own opinion. The information are collected through various sources. I am grateful to those who have opened my eyes, namely Ilya Profatilov, Kevin Bazier (Tainan Mantis) and many others. This doesn't represent any other's view except my very own. Any mistake is solely mind. Please feel free to correct me.
I think a lot of the differences materialized because of the different methodolgies which are based in the teaching philosophies of the various masters. For example, the older version of TJPM based more on a body of techniques which are collectively known as Mishou (some seems to suggest that this is rather a form). This explain why it used to be very few students that the Grandmasters would accept and transmit the system to mainly an individual as oppose to many students. From there came Luanjie and Bazhou (during GM Liang XueXiang's time when he decided to accept a large number of students). Then came Xiao Beng Bu which was created to hide the Luanjie. Later another version of Beng Bu, which is the most recognizable PM form of all time, was created. Since it is taught in Yantai county, the old capital of Shandong, it is also called the Yantai Beng Bu. It's original name Da Beng Bu is now rarely in use. Finally a prototypical version of Dzai Yao was created. It is then further developed into 7 sections. At the core, the training philosophy is deeply rooted in Mishou where individual techniques are practiced mano a mano in most hardcore closed quater combat manner. This I have a taste of from my training in CCK TCPM which is a branch of TJPM. In a way, forms were created to keep other students entertained while the masters work closely with a selected number of students (1 or 2) in the Mishou type of training. If we look at the 12 Characters of Taiji (Meihwa), we see that they are somewhat of an encoded series of drills of conceptual nature, which are expressed through various combinations of techniques (ie Feng Shou has go-lu-tsai in it).
Meanwhile no one exactly know what Li Sanjian taught but then by Wang Rongshang time Longfist forms would have been inseperable to the 7* system. From there Chaai Chui, HeHuJiaoJia and others were added. The main reason that there are so many forms and the high regard of form in 7* is IMHO mainly because of its Longfist background. Later on Ling forms became another important feature of 7*. If we examin the QingTsao 7*'s version of 12 characters we see the Longfist mindset is deeply encrouched (ie Beng, Pi, Tiao and Chong). It is also heavily technique based rather than concept based although some people argue that it is also concept based. But this somewhat hard style philosophy experienced yet another face lift by LGY's or WHF's time. Beng Da Diao Jun (swift and fluid - characteristic of Eagle Claw) replaced Beng Pi Tiao Chong (rapid and bold - that of longfist). This is largely IMHO a change due to coming in contact with Eagle Claw in Ching Wu, which was pioneering in creating a universial national art of China. The adaptation of these four words would make the gap between Eagle Claw and Mantis even smaller for Ching Wu students to learn things quickly, and switch from style to style without seemingly having 2 vastly different looking style. This would explain why HK 7* and mainland seems a bit different and instructors of Mantis origin of Ching Wu such as TJPM Grandmaster Chiu Chuk Kai adopted the latter deviced 12 characters. Drills in 7* are quite similar to Taiji's excepted often 7* drills are often broken down into smaller pieces and limit the student to one side of the drill as oppose to TJPM's switching role constantly.
Kung Fu as martial education has to be pragmatic. It has to evolve according to the time and the need of the people. In the case of PM it has been so. Having said that we must remember those who make the evolution possible are well learned (martial wise) masters. They don't create or change things out of a whimp and pass it off as legitimate material. Until the time we all fully understood the profund wisdom that is in the system. I don't suggest anyone to make the system fits you. Rather you should first learn how to fit with the system. I agreed that way back when Tanglang is Tanglang and no specific tags were assigned. It would be great if we can do that again but currently it would take a major miracle to bring all sides to the table. Anyway, lineage dispute and secrets are major obstacles in promoting an awesome art such as Tanglangquan.
Just my thoughts on the matter.
Mantis108