You will find many LuLa posters who swear by SilverEfex. My own preference is for LightRoom.
I have SilverEfex Pro and LightRoom, and when I first got SilverEfex I played with it quite a bit and got some pretty good results. If I recall correctly, SilverEfex comes with a big bunch of presets in different "styles," from elegant to grungy, high or low contrast.
Besides the presets, the main tool for individual modification was similar to the local adjustment brush in LR. At the time, either LR didn't yet have a local adjustment brush or else I had never used it, so I found it difficult to apply a round brush to a non-round object in the image.
Using the presets, I never felt I was in control (it was a little like posting a raw file on LuLa and asking people to do their best B&W rendition, and then choosing the one you liked best, with no idea how to get the same effect in another image).
In LR I always make the best color version I can before converting to B&W. The sliders in the B&W panel give me lots of (global) control, and I always test all of them, since sometimes what looks green actually has more yellow than green, for example.
And if I need local adjustments, I can still do them with the local adjustment brush.
So, my feeling is that in LR everything I do is under my control, and I never felt that way in SilverEfex. Of course, if I spent as much time learning SilverEfex as I have put into LR since version 1, I might feel differently.
That's my two farthings.