I can't really coment on CS6 as I use LR 3, Elements and Nik Silver efex. What I like about silver Efex is that one can achieve a desired result whether it is high structure, high contrast, high key, low key or even film noir etc very quickly. These can be done in the other software bundles but it takes a lot more time and effort. I love the ease of use of the sliders, its like multi-contrast or polycontrast in a slider. Love how easy it is to boost structure/sharpening in selective parts of the image for visual highlights. The vast array of available presets is also great, you can pull down a preset you like and tweak it very quickly to your own taste. Silver efex and topaz denoise are undoubtedly my 2 favourite plug-ins. I do think one has to be careful in efex as it is easy to overdo it.