Here's an interesting quote from an interview with Yasuo Kobayashi (the original interview was Japanese only). It does relate to Fred Little's post a bit:
"While we're discussing this, as far as I know koshi-nage was not practiced much in the beginning. After Nishio and Kuroiwa researched it independently other instructors began to steal their techniques."
Heard that from someone else as well.
To the best of my understanding, Koshinage is more of a Judo type move.
[At least it appears that way from my limited knowledge of Judo... which really is zilch]
But, I am glad, in a way, that it exist within Aikido, as its this type of movement which shows the natural extension of Judo in relation to Aikido - [and though not this technique, you can see where BJJ fits in as well once you start playing with grappling]
Think more of it in terms of distance as to what is effective, I heard someone say once... and it seems to hold up. [All in all, its all jiu-jitsu - just got split up]