I believe the consensus on this forum is that the info from Eric's site, is out of date for the newer versions of the Epson AWB driver. This has been documented on this forum in several discussions.
For the 4900, or 7900, 9900 the recommended path, is leave the image in sRGB mode, and use "Let printer manage colors". You select this in the box where you have the options of no color management, let photoshop manage colors, etc.
This is totally different from Eric's workflow, which allowed for soft proofing.
If you convert a color image to B&W with either Lightroom or a tool like Silver Effects Pro, make the conversion to B&W but leave the image in sRGB not greyscale.
I have had very good success with both the 9880 and now the 9900 with this workflow on B&W prints from the Epson Driver.
Sincerely
Paul Caldwell