I talked today with one of the IBM web server developers about
the use of http post method vs. new http methods for ipp. His view
was that there would not be a significant performance or load
difference for these two alternatives. He thought that defining a
new protocol was the worst choice.
He also told me that in IBM web servers, new method handlers
could be written by anyone and bound into the server later, so
defining new methods on IBM servers doesn't require the server
code itself to be changed.