I am using the AFL/AEL rear housing trigger to focus and then the shutter release to expose. This allows me to focus once on a subject and then shoot several times without a refocus. These were also taken at ISO-100, 1/320th at F7.1-F/9. AF seems quite fast and great image quality.
Ted, see you and Barbara in April.
What functions did you set for the rear button focus? When I was trying to set this up, I wasn't getting the proper focus behavior.