i have no experience with anything other than the tk2, which i currently own. it is a stiff bike, but that is only in comparison to my road bike (caad8), so may not be that stiff compared to other track bikes. the aero qualities are certainly good, likely better than the bmc for kilo/pursuit duties. the only knock on mine is the crappy rear dropout, but i think felt fixed this with this years model. bmc's are tight, though. don't think you can go too wrong here with any of the choices.
also, the geometry of the bikes is 73 for the bmc, 74 for the felt and 74/74.25 depending on your frame size for the specialized.