You are correct to put the traction tire on the front, and there are numerous threads already on here explaining the rational in the MTB, Cross, and winter forums, expanding on what I quoted from Sheldon. There may be a few circumstances under which people benefit from more traction on the back, but I think these conditions would be very rare.

Slick or nearly slick tires may be sufficient for your needs and they will be faster. They will not be optimal for control on loose surfaces. In some cases, it might make sense to slow down a bit more on loose corners in exchange for the lower rolling resistance and higher speeds that slick tires offer elsewhere.

This concurrent discussion may help, although I think they are only referring to 700C tires, which may or may not be what you are after

http://www.bikeforums.net/showthread.php?t=558260