I have also "heard" things about the owners of treetops too. Some good and probably more negative. Check out this forum http://www.belizeforum.com
also and type in Tree Tops.
From what I gather they owners have strong personalities. Some people think they are great others don't like them. You either love em or hate em type of people. Does this make them bad, depends on the type of person you are and what you expect from an accomodation when traveling.
I am not sure about them based on what I have heard so I decided it would be best to chose another place. I might get along fine with them. However, this is my wedding/honeymoon trip and I don't want to take the chance of having a negative experience.