I, too, like my recently-acquired 300f4L Is. Yeah, clunk on IS action but the lightness is good. I admit I reach for the non-existent zoom sometimes. Glad I found it at a good price. I chose this over the 100-400 as I decided I's not shoot the range 300-400 enough for my clients. Tried a friend's 100-400 and can see the appeal but I saved a fair amount buying this 300 prime.