As an open source and open content advocate, I am interested in the debates in the OER community about licensing, particularly CC-BY (attribution only) vs. CC-BY-SA (attribution and share alike). To admit my bias, I am, and have always been, a copyleft advocate, so I'm a card carrying member of that latter group of those that believe in share alike.
Now, there are certainly many good reasons to choose either license depending on one's priorities in license choice. Nevertheless, I always chuckle when the CC-BY advocates condemn CC-BY-SA while championing that CC-BY allows for users to make choices about licenses they wish to use, whereas CC-BY-SA doesn't allow for licence choice. As Sam Varghese pointed out during a resurgence of a similar debate (2007) in the open source community between the GPL and BSD people,