Having read Christopher Clarkes's "Ramblings from a ten foot hut" (Iain, good suggestion), I was interested to read that Hangetsu was an invention of Funakoshi to combine Seisan and Sanchin. Specifically I found it interesting that the theory is that Hangetsu-dachi was an attempt to make a stance that enompasses the lessons of Sanchin, but with a longer, more shotokan-esque "feel" to it.
Having come from a shotokan background and now studying Goju-Ryu, I'm intrigued by how many things that were presented as sacrosant and historic are actually quite distinct to shotokan, quite "recent" and can be traced either to the advance of competition or to the move of karate to Japan. For example, I look at how shotokan kokutsu-dachi isn't in Goju-Ryu, where Goju-Rye tends to have either kokutsu-dachi as zenkutsu-dachi with the head turned, or uses niki-ashi-dachi instead.
I wanted to ask 1) is shotokan kokutsu-dachi another example of something where the original stance (Niko-ashi-dachi?) was lengthened to make it more shotokan, and 2) are there any other good examples of changes and new techniques where the point of change can be pinned down?