I too, am planning on replacing my Tamron 55-200mm with this one.. How is the bokeh? I would mainly be using this for portraits on a tripod, so no IS = no problem to me.
I love this lens. I have had no problems with it. The bokeh it fine. I never really paid any attention to it really. If I were you, go down to you camera store and see if they will let you take some test shots with it.
If you goto my flickr link--on the 3 or 4 page there is a shot called "Love"
It was taken at 70mm. right now it is the only "portrait" shot I have with this lens.
On a side note-----How would you test for Bokeh
I have not a clue