I wish you had published it back then too.  For me one of the most
interesting aspects of Mahler's compositional methods has always been his
layering on "with enriched heterophony" as you put it.  I can't imagine
the source of this method -- it doesn't fit into any historical analogies.
And its function is not merely decorative; it's a part of the composition
itself, as he uses these musical scraps (not a good word for something so
vital).

It's still hard for me to understand how someone so creatively enriching
as Mahler was so totally dismissed by the musical cognescenti for half
a century.

Bill S