I have been working with Topaz BW Effects 2 from Topaz Software which at only $60 provides a very cost effective alternative to Nik Softwares $200 SilverEfex Pro 2. I have been getting very good results with files sent to the plug-in from Lightroom. The image below is a street shot grabbed quickly on the X-Pro1 and the 18mm XF lens. The .raf file raw file was opened straight into BW Effects 2 once I had imported it into Lightroom, and all further wrk was done there. I think it produces a much more detailed and controlled result that Lightroom alone, and I would recommend it.
Gerry Walden's Blog 