I am nearly speechless that you would try to use the ISS as an example of a "success story". It was mind boggling behind schedule and over budget, though turning it in to an international project is partially to blame. The core is based on existing Russian design. If they had just launched that and kept it simple it would have cost a tiny fraction of what it did and accomplished nearly all the science ISS has done.
The fundamental problem with the ISS is its bled NASA and the manned space program white. NASA hasn't done ANYTHING useful, in its manned program since Skylab, other than maybe Hubble. They built Shuttle to fly to the ISS and the ISS so the Shuttle would have a place to fly. It resulted in NO breakthroughs or progress worth the price tag.
So what is your point on Falcon. I think you just agreed with me SLS is hopelessly uncompetitive and SpaceX approach is really smart.
SpaceX is trying to get to space cheaply, safely and with a very high launch rate.
SLS seems to be trying to come up with the most expensive, impractical and dangerous solution possible, just to keep funneling money to Lockheed, Boeing, ATK, etc. Its as if they are TRYING to develop a system that is sure to fail or be cancelled.
Note the proposed launch date, 2017, just long enough after the 2016 election so the next president can cancel it and start over.