I just came across this unpublished ms. by Halle that Tobias Scheer seems to have preserved for posterity. It’s a very nice discussion of the (non-)connection between affixes’ cyclic status and the  level at which they are added.

Update: See Cole’s (1995) Handbook of Phonology article on Cyclicity for an overview of subsequent analyses of Diyari and Vedic Sanskrit, as well as other useful related material.