Being disfellowshipped would result not from reading other information, but starting to raise questions about the accuracy of Watchtower information, which is a natural result of research. ~ jwfacts
From my experience, this is accurate. If you claimed you were reading religious materials to learn how to refute it, that would be acceptable. If you are reading religious material and supporting thoughts that are in conflict with WTS, then that is "apostasy".
Reading COC is apostasy just because Ray was the #1 apostate. You would really have to "wiggle" to get out of that if you were caught with it.