I will say this first: I love the 400. To be honest, I think it was the best gear purchase I've ever made.
That being said, I think that the 300 f/4 IS is more versatile than the 400. It has IS, it's an f/4 which is good, and it'll still work with a 1.4 TC to bring it up a step if you want the extra reach. The IQ is stellar.
While the 400 is amazing, IMO, the 300 is a better all around lens for what you're looking for.
I will now sit back and watch everyone disagree with me.
You've pretty much summarized my impressions based on several bajillion posts around here and no ''hands on" with either. It really helps to hear from people who've played with both in the field.





