I just passed your store in the Lincoln Square area, and was delighted to see that you were having a sale. This was exciting as I have just started jogging again, and am in desperate need of new running clothes. Specifically, new sports bras.
I went in to try some on, and before I say anything, I'd like to mention that I am a "traditionally built" Ashkenazi* woman (read: large-bosomed), so I have certain requirements in a sports bra. Like support. Unfortunately, you, lululemon, seem to be confused. You seem to think that sports bras work on proportional scale. This is not true. Just because a size is larger, and technically "fits" does not mean that it is useful to someone of that size.
Compare to your far superior "bounce breaker" which you did not have in my size. According to the site, the "marathon" bra provides maximum support. Really? Just look at the difference. The "bounce breaker" has an inner bra for extra support, mesh panels that separate different parts (and keep the bra from becoming a "two puppies, one bag" bra), and far less annoying straps. If by "support" you mean "covering as much of your chest as possible," then yes, the "marathon" is more supportive.
*Ashkenazi Jews are Jews of Eastern European desecent.