  For well-generated complex reflection groups, Chapuy and Stump gave a simple
product for a generating function counting reflection factorizations of a
Coxeter element by their length. This is refined here to record the number of
reflections used from each orbit of hyperplanes. The proof is case-by-case via
the classification of well-generated groups. It implies a new expression for
the Coxeter number, expressed via data coming from a hyperplane orbit; a
case-free proof of this due to J. Michel is included.
