I agree that the MT CDs are well researched / produced and very good value I would recommend them (and often do) to anyone interested traditional singing. They also bring to the public fine recordings that would not be released through larger record companies.
As to the question of durability of CDR and pressed CDs here I can talk from experience not opinion. I was involved in an extensive life test of a wide range of audio storage types. The CDRs performed significantly better than pressed CDs