The reason I am confident the problem is with Pages 5.n goes back to a matter I had getting EndNote 7 to work with Word 2011. The tech support person at EndNote was outstanding. The investigation was meticulous, and we were able to prove that the issue was with Word 2011, not EndNote.
During this same incident, I tested all of the functionality of EndNote 7 in Pages 4. There were no issues. In light of all of the problems with Pages 5, I have not tested EndNote 7 in that app. Why bother.
Finally, I have found EndNote 7 to be very stable. I do not use any of the cloud or sharing features of the app. As always, there are sync issues when your biblio database changes, but these are neither problems in Word nor Pages.
Finally, the best alternative I have found to EndNote 7 is BookEnds. However, BookEnds does not have the cite while you write features of EndNote.
Bottom line, Thomson is a serioius publishing company whose products and services support serious professional users. They publish massive databases in finance and econ, and they publish other databases, including ones used by the news and legal businesses. I have used EndNote since the first verision. The app has been remarkably bug free. So, if you hare having issues between EndNote and Pages, look to pages for the sources of the issues. The most likelly place for problems will be in App Sport libraries. If you ditch the drivers, it will not have any impact on your biblio databases.
I hope this is helpful.