A Passenger Through the 2 Train

While waiting to catch the train downtown to get from Medidata HQ to PG Inc., I was wondering:

• In a overlong exposure, would a photograph show more metal or windows of a passing train? Does that have more to do with timing of the release or length of the exposure?
• Would it be possible to get a clear shot through a train if, at releasing the shutter the right moment, the view through the windows was clear?

Preliminary results of this experiment are unclear. This image came from a handheld 1/25th second exposure of the front car around 2:30 pm. I couldn't manage to make this shot during rush hour, the train would be too crowded for a clear view. I probably would want to time this shot for a release of the shutter as the right side of the train's window breached the line of the support beam, closing it as the left side of the window touched the left side of the support beam on the right. But then one edge of the frame would show a moment in time nearly 1/25th of a second later than the other edge. Is such a long exposure photograph showing action still an accurate representation of the moment? Would I see different results with a focal plane shutter that moves left to right instead of up and down?