I think you should do what you feel drawn to do, and know your own mind. If you are a kagyu and you want to do an academic or scholarly study comparing the various traditions, this will probably benefit you. My tradition is kagyu, but I have learned a lot studying all kinds of traditions. Also, what i have learned through my Kagyu teachers has given me some "interesting ways of understanding" other traditions. But if you are sort of grasping at straws, trying to see what one has to offer that another may have left out or whatever, then that is probably more of a waste of time. This certainly doesn't mean you won't learn something useful, and I think it is good to read stuff from various traditions, but, I think, it is better to keep your feet planted in one tradition. I don't think it is ever a waste of time to study and learn about things you do not know. Currently, I am alternating between books on mahamudra and German expressionism.
Profile Picture: "The Foaming Monk"
The Chinese characters are Fo (buddha) and Ming (bright). The image is of a student of Buddhism, who, imagining himself to be a monk, and not understanding the true meaning of the words takes the sound of the words literally. Likewise, People on web forums sometime seem to be foaming at the mouth. Original painting by P.Volker /used by permission.