going US so wan to bring as backup.
And end up like one post which I read.2.8 for the better subject isolation qualities
US streets may not have so many places for u to camp and zoom with this lens.Personally i find the 70-200mm range very useful and indispensable, especially for portrait shots and street shooting; for capturing those candid moments of strangers and friends alike, allowing you to shoot from a distance.
yes you are right, depending on your photography style.Its not true that this range is "useless". When you need it, you would beg to have it. It all depends on your photography style. I was in Guilin last Dec and was on a "mountain" at the right time to shoot the setting sun. The f4 IS was good, but I had to add a 1.4x converter to get the additional reach.