Thats pretty much it I think. Unfortunately it's very speculative and opinion of effects differs from person to person. When looking at a particular kava, you'll want to find out what its chemotype is (most retailers make these available, there's also a big list in The Pacific Elixir I believe) which will tell you the relative content of kavalactones (e.g. this kava has more kavain than anything else, followed by dhm followed by so on). From there you can maybe get an idea of how these kavalactones effect you.