Mileage varies
Ben Long reviews Silver Efex Pro and correctly points out one of its best features
The Black and White adjustment in Photoshop is very good because it allows you to make changes to specific color values in your image. The problem is that if you tell it to darken the blue tones in an image, every blue tone will be altered. Silver Efex scores over Photoshop?s built-in Black and White [JB: or Lightroom or Aperture] because it can alter tone and contrast of specific areas, based on color, but constrain the alteration using an automatically created mask.
You could achieve the same effects in Photoshop using multiple Black and White adjustment layers, each configured differently and constrained using hand-built masks.
That’s what I do, and I don’t find it too troublesome.
At the moment Silver Efex Pro’s probably the best b&w conversion and grain utility around, though its film & grain recipes don’t take account of differences resulting from choice of developer or your agitation method (you can create your own recipes if you’re really anal). It also costs $199 – even as someone who does a lot of b&w, I don’t think it’s good value for money. And if I wanted to emulate film, I’ve still got my old film camera (as well as a brand new toy).