Well, I think that the main reason people use post processing and bring in alpha planes is either to make up for the lack of features in an program like Vue or Bryce, or for memory problems that can result of too many models being imported... I do a lot of vegetation pictures using alpha planes for the plants, because when I tried the using models, the rendering times shot through the roof, and the plants didn't look as good as the plants I got as alpha planes.. Another reason is that you want variety in your pictures... If a picture is using trees, you can always tell if a picture is Vue or Bryce from the type of trees in the image... I think at some point, you want use different type fo trees, so that it doesn't look like the stock trees that come with the programs, so you use alpha planes.. In the end, I think that the important thing is, are the tools you're using helping you make better art? If the answer is yes, it doesn't matter what it's classified as, whether it's vue, vue with post processing, or vue with alpha planes, as long as the render was done in Vue or Vue related..