My opinion is many personal trainers don't really know what they're doing, and elite bodybuilders' approaches many times are not ideal for joe average natural bodybuilder.
That said, it's mostly a matter of how much of a fan/admirer of him you are personally. Zane accomplished a lot in his day, had a body that epitomizes aesthetic development in a lot of people's minds, comes across as being very intelligent in his writings, and from what I hear is quite hospitable in person, so I can understand why he would have many great admirers. If that's the case for you, then it's worth it.