In which direction do you believe Meyendorff to be "biased"?
Sorry for the word, English is not my first language and many times I choose words not properly.
I think that Meyendoff is "apologetic" of his (Russian) Orthodox view. As I prefer not to base my historical knowledge on Catholic "apologetic" historians (as the Joseph Lortz for example), the same I don't fully rely on "apologetic" Orthodox historians.
Of Meyendorff I've read his "The Orthodox Church: its past and its role in the world today" which historical part is apologetic and quite untenable: fox example his way to write about the 17th and 18th century uses the same strategies used by apologetic Catholic historians about the Borgias...Ok Meyendorff is by far better then other Orthodox apologetics who for example arrive to deny that Lucaris was a pro-Protestant, but his history is still very sided with his own faction.
Anyways I consider both Meyendorff and Lortz good and serious authors, simply to be read with circumspection.