Jerry Spagnoli (NYC) and Mike Robinson (Toronto) both shoot commercial dag portraits. While the Beq. process is "safer", the extra slow speed makes it problematic for portraits (3 mins f 8 in bright sunlight). I know Jerry uses a thermonuclear power strobe bank for his head shots, and also uses the faster Br-Hg method. His dags are second to none. Mike's work uses natural light and consequently has a very different look.
Regarding production speed- figure 3 hours to polish, buff and sensitize 6-8 plates. I prep my plates in the morning and run a bromine test in my driveway before heading out to shoot. Back in the afternoon, I develop over the Hg pot and fix - 8 plates take a little over an hour, not including gilding time.
I've thought about offering a portrait service, but at an hourly rate plus plate costs I feel it would only be viable in a major city -- not here in the boonies of Connecticut.