After updating the firmware I have now had several times out with the lens over a month or so. I am sure that on Focus Speed priority I have more trouble getting focus and get more misses. The increased speed just isn't significant enough to worry about using this setting compared with the normal setting. Anyone else found similar?
I have not had that issue. In fact, I expected to have a few missed focus issues, but I have been pleasantly surprised at how accurate the focus is. Not to say that I don't miss focus on some shots, but I tend to shoot small, quick birds in trees and bushes and I don't care what lens you use, when photographing birds, you will miss focus on some shots.