I am thinking of buying one of these lens for landscape photos. I already have the non-IS version of the 70-200 f/2.8L. So do you guys think I should upgrade to the IS version or get the f/4.0L IS version. I usually do not shoot at dusk or early morning light. If I have to I always have the non IS version. Also, which lens will be good for the new 5D2 camera I will buy in the future?