In reference [8] we have considered a wide class of "well-behaved"
reducibilities for sets of reals. In this paper we continue with the study of
Borel reducibilities by proving a dichotomy theorem for the degree-structures
induced by good Borel reducibilities. This extends and improves the results of
[8] allowing to deal with a larger class of notions of reduction (including,
among others, the Baire class $\xi$ functions).