I persoanly dislike post processing because I dislike having to use multiple programs to achieve an effect so I tend to try to force the one program i'm using to do what I want. In my case it's got nothing to do with trying to stay true to the fractal math, it's just lazyness. My feeling though is that if you are using fractals to illustrate exactly where something is being plotted and how, then you want it simple, you dont want to do anything to it after the computer finishes because if you do, you can't very well tell what the original formula was doing. But if you want to create art, then for heaven sake go create art and dont worry about what anyone says. About your choice of tools or your methods of using them. Or even the final product (unless you're making it for someone specificaly).