Today I just played with the Tokina 28-200mm f3.5 and there's a view of the result below.
The greenscreening was done within Sony Vegas, I would have used CompositeLab but it would have taken a while to render even though the results would likely have been much cleaner.
Anyway, tomorrow I'll be trying out the Canon 100-200 zoom and we'll get a first hand comparison of the two zooms.