Originally Posted by Mellyrose
Just wanted to chime in quickly because I noticed the "twist" versus "push/pull" factor. When Phil first put the 100-400 in my hands, not only did I think "MAN, this is heavy" but I was like "wow that is awkward feeling" with the push-pull since I was used to shorter twisty zoom lenses. Not 10 minutes later, I was used to it. Even though I use twist zooms still, once someone lent me a long lens which had the twist feature, and I thought that for aviation photography and the speed we have to zoom in an out while panning, the push pull is much more efficient. Obviously, this is just my opinion, but I wanted to share since I had the same viewpoint as you before I started using the 100-400. Also, I promise, you do get used to the weight. I have serious neck problems, and if I can let that thing hang around my neck for 10 hours, anyone can ;)
Do what feels right for you, but any lens is gonna cost a good amount of money. I think we just want you to be satisfied and really happy with the final results!