Some members may be interested in a fairly recent book though obviously of
less interest to traditionalists.
"Early Buddhist Metaphysics -- The making of a philosophical tradition" by
Noa Rankin, RoutledgeCurzon 2005.
A very interesting book but very expensive. The back blurb begins "This
book provides a philosophiocal account of the major doctrinal shift in the
history of early Theravada tradition in India: the transition from the
earliest straum of Buddhist thought to the systematic and allegedly
scholastic philosophy of the Pali Abhidama movement" etc.
PS: Concerning upekkhaa-sati-parisuddhi -- I would prefer not to enlarge
upon my comments on this term at present to avoid the kind of unskilful
behaviour we experienced not too long ago here. Too many fondly-held
assumptions might be challenged.