I bought the new Tamaron 70-200 VC. All of these are handheld on F-2.8. I found that I have to be more disciplined on my button control to not blur the picture as my F-4 lenses were more forgiving... The only light used including the indoor pictures is available light.
I like the lens. As long as I do my part the lens will do it's. I noticed with some sunset pictures that the vignette is prominent, but LR5 makes it all disappear..
Could be considered heavy by some but it's ok for me.
The collar comes in handy. I lengthened my neck strap some, and stick the collar into the top of the pants so it's supported while walking...
I don't know the name of the quick tripod disconnect I have, but it is flat and it closes from the side. The collar mount is thicker so I can't close it. I'm going to have to find something to attach to the collar that will allow me to still use my quick disconnect...