ed rader wrote in post #17327199
I did use the 100-400 original and the 70-300L side by side with no issues but I always looked at my longer zoon as my 400mm wildlife lens. I shoot a lot of landscape with the 70-300L and there is a big difference between 100mm and 70mm for landscape. not to mention I do love the 70-300L and without hood it fits in my jacket pocket. hmmmmmm
If you can afford it, I would hang onto the 70-300L. It is nice to have a smaller, lighter telephoto option in your kit for those times you want to travel lighter. Like you, I think of my 100-400L as more of a wildlife lens, but I simply do not have enough space in my travel bag to bring along both telephotos. So, the 100-400L will do double duty as a landscape telephoto, too, when I bring it along for wildlife and leave the 70-200 f/4 IS at home. The 30mm difference at the short end of the zoom ranges does not affect me, as I also travel with a 24-105L. Anyway, on our Alaska trip last summer I just left the 100-400L on the 7D all the time, even for my landscape shots. The gap between 105mm on the 5D3 and 160mm equivalent FOV on the 7D at the short end was never an issue.