The entries are based off of the Ales. The Ales-ales are the foundation piece from which all other elements come off - from an attribute perspective.
That said, originally I learned Masukan Kaki from Pamur. The eight that I currently use were derived directly from Pamur as is. They are great and they taught me many things. They still teach me. I've modified them on a superficial level but they are essentially the same as I was taught. Very good - though the purpose of me writing these pieces isn't to get into all of the "what belongs where and where did it come from" discussions. Personally, I think that will only detract from the value of it. What is valuable is not the what and where but the "why!" That's what I'm really wanting to communicate.
That said, even though the Masukan Kaki or Leg Entries have so profoundly changed how I think about combat, they are not the final solution. They have shortcomings. It's the same shortcomings I've found with most footwork that exists in the martial arts. That is to say, that moving your feet in order to move your body is not always very fast. Or to rephrase, it's never fast. Especially when compared to an attacker's hand speed.
The shortcoming is then, that when an attacker is striking you repeatedly, they do not wait for your footwork to catch up. Instead, they simply strike and strike and strike until you resign using footwork in that manner. Especially if your footwork is the source of your evasions. I suspect that if you really look around at systems that have extensive use of footwork as their evasions that you'll see those systems actually use blocking in real time combat because there hands are faster.
Additionally, to use Masukan Kaki or Leg entries requires that you are able to close on an attacker and bridge the gap immediately - at least within the time space of a single hand attack. In my own experience that has proved to be reasonably difficult to do in real life with any sort of consistency. The mind is an amazing organ and people are quick to see a threat and change and adapt their movements. This makes it difficult to apply a Masukan Kaki unless you can see the attack coming, or just get plain lucky.