Other authors to be very wary of when it comes to Transubstantiation and the proper meaning of the sacraments:
Karl Rahner
Edward Schilebeeckx
Nathan Mitchell
Thomas Groome
Thomas Richstatter
Jeffrey VonLehmen
William Shannon
Joseph Martos
For an excellent article about the "dumbing down" (if not out right heresy) of the sacraments, please see this article by Fr. Edward O'Connor, C.S.C.:
http://www.catholic.net/rcc/Periodicals/Homiletic/June97/mcbrien.html