I'm shocked to see this thread turn up today as I just discovered this fact on my morning ride. Last night I swapped out my 100mm, 7deg stem for a 110mm, 0deg stem and popped out one of the spacers. About 5 miles into my ride, I realized that my pelvis was oriented vertically on my seat and my back was arching toward the bars, creating as 'S' shape going from the top of my head to the bottom of my pelvis.
Once I realized this, I rotated my pelvis forward so the pointy part of my sit bones was now in direct contact with the saddle. This was instantly more comfortable. The right side neck pain I've been getting is completely gone.
It did point out the fact that my seat is still slightly too low and too far forward. I'll be making the adjustment tonight, looking forward to riding tomorrow.