Right now I use a Canon 20D with a Canon 100-400 L IS. The 100-400 I have never been quite happy with. It seems mine is alot softer than everyone else's. I think i'm going to sell it in favor of a two lens system.
I'm looking at both these to replace my 100-400:
Canon 70-200mm F/4 L
Canon 300mm f/4 L IS
I would also get the Canon 1.4x extender.
What are your thoughts on my choice? Will the new lenses only be marginally better or tons better? Or will the 100-400 be better? I did drop my 100-400 on concrete from about 3 feet in height 2 days after I bought it, but it didn't even get a scratch. Maybe I should have mine looked at first to see if anything is wrong with the AF or IS, or maybe even a bad copy.
Also, if I did go this route, would the 300mm prime with IS be better than the 400mm prime without IS? I've heard great compliments about the 70-200 f/4, so is the f/2.8 even better? I need to control my $$$ at some point so I think i'll have to stick with the f/4.
Any help or opinions appeciated!