Sigma 100-400mm C VS Sigma 150-600mm C

I purchased the Sigma 150-600mm contemporary a couple of weeks ago, and I'm considering maybe switching it out for the Sigma 100-400mm contemporary for a couple of reasons. Whenever I go out shooting, for pretty much exclusively birds and other wildlife, I walk around and handhold as I'm not really one to stay in one place, and I found that lugging this lens around with the shoulder strap or by hand, along with my camera backpack, to be a little much and really hard on my shoulder. The 100-400 is almost an entire kg lighter, which is super enticing. The 100-400 is also a fair bit shorter as well, with the 100-400 and the included lens hood being almost the same length as the 150-600 without one, and I imagine this means that the camera+lens will swing far less annoyingly when hanging from the strap (I'm also a little socially anxious so I'd rather not stand out as much either)I tried shooting things at both 400mm and 600mm to compare, and honestly I didn't see much of a difference in most cases, although someone with more experience can probably weigh in on this, especially if there's a difference in image quality and performance. The extra 200mm did only cost me less than $100 more though, but I'm questioning if the significantly added weight and physical length actually outweighs that at all. via /r/photography http://ift.tt/2gWdI9a