Jag,
In general, hardpack tires are made from harder compounds and soft terrain.. softer. The 756 would probably wear much quicker, especially on the street. The new 773 is really soft, didn't last long on summer tracks in Oklahoma. My fault, should have changed it. It does get a helluva bite in the soft stuff though!
DUNLOP SITE LINK
The cutting-edge D739 tire delivers outstanding performance in hard-pack conditions, and improved cornering grip in all terrain.
The D756 offers outstanding intermediate-to-soft-terrain performance, yet its versatile design gives it a wide range of ability on harder surfaces.