@ebiggs1 wrote:Trevor,
"The point about newest bodies may well be correct, ..." The point doesn't stop with the newest bodies although they do take full advantage of f2.8 or lower. A faster lens will always focus faster. Yeah, in great light you might need a computer to measure the difference but it is still there.
It is hard to critique a photographer like you that seems to get the best out of his gear but it is still a fact. There are other factors that will effect focus speed besides f2.8.
I would never doubt that Ernie, and I totally respect your comments in this area. I would have to say that I simply have no experience with needing that capability. Somehow I just use the lenses and bodies as I need to - rather oddly perhaps I have not kept up with the latest capabilities of bodies and lenses. I even still shoot a lot with my Canon 60D's (just 'cos I like them!) and they are what... about 9 years old or thereabouts. Sadly I am a living fossil (as my stepdaughter is prone to remind me... 
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My comments are never intended to be seen as absolutist and should (I hope) be taken as part of the whole post I made. We tend to get minimal information of the intent, types of subjects or conditions and constraints upon which we are asked for advice to suggest a solution. I always seek to get more details in those areas (as you have doubtless seen multiple times), perhaps there should be a form one has to fill out before asking "what should I get, or in this case what is a "good" lens. 
