Take a closer look at the polygon solution I showed above Dave. Yours is just a slight refinement. It just eliminates the inner triangle (a good thing btw) and then adds a tad more geometry for the stripes that could better be left out and the stripes just texture painted on a simpler 6 polygon model. I did not have a stopwatch but it took about 30 seconds to optimize the solution
However, the point is the original question was about using birail and people are clearly confused about using Maya's very powerful and useful NURBs surfacing tools (i.e. trying to use three rails for a BIrail).
So I thought it was a good opportunity to demonstrate a birail solution and explain how to use the birail tool properly.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675