So I have been toying around with the idea of picking up the panny 2.8 zooms. My current lens portfolio includes the 9-18, 20, 45, and kit 14-42. While I love the 20 and 45, I am missing using a zoom and am thinking of starting by getting the 35-100 and selling the 45 to help offset the cost. The only real opportunity I had to test out my prime "kit" was a trip to Chicago in the late fall. I sort of detested the idea of changing lenses all the time while shooting, so i just left the 20mm on the whole day. I ended up with some images that i was extremely happy with and loved the experience. However, for the majority of the time, I like to shoot pictures of my dogs playing or training, and shoot pictures of other dogs training. I also do a lot of rock climbing and do a couple trips a year to Colorado or somewhere similar to do some mountaineering/hiking. While i love the 45 for its sharpness and contrast/color, its not ideal for the things i use it for (mainly action shots), and while several hundred feet up on a rock wall, or backpacking/hiking, changing lenses is not ideal. I play around with portraits, and would like to even more in the future as well but it isnt my primary subject. Id also like to play around with sports photos in a high school gym (mainly wrestling). So to summarize, my questions are: How does the IQ of the 35-100 compare to the 45 both in sharpness and contrast? Thoughts on ability to isolate with 2.8 vs 1.8 the subject since i'll have the ability to move farther away and zoom? Is 2.8 fast enough for shooting in an average gymnasium? Other concerns or thoughts on my situation? As always, all comments are appreciated. Thanks in advance!