Never tried a Prior, but they seem to have almost the same geometry as SG Speed.
I tested SG Race T (the old shape - same as Speed) and simply LOVED IT!!! Best board I ever rode by far!!! and I rode Nidecker, Burton, F2, Coiler (old RC model), Goltes, Xtasy, Virus Nightmare and Pogo Impact. But in the same time, it's the only metal board I ever rode, so maybe that's why I loved it so much...
I guess I didn't help you much... :o