I've had the 200/2.8 for about 10 months. Cracking! Its superb. And with the 1.4 I could see no noticable drop in quality. I also now have an original 300/2.8 APO G, the first model. The 200/2.8 is certainly sharper, and with the 1.4x they are about a match.
Sorry, no personal knowledge of the 300/4. But when I was shopping for the 200/2.8 I considered the 300/4, but discounted it.
I don't normally recommend a loook at photodo.com - but the numbers stack up.
Please be aware that I am slightly bias, I am selling my 200/2.8! But this would have been my opinion anyway
See also my http://MaxxumEyes.com
website, there are links to on-line user reviews of both the lenses you consider.
I view it as this.200/2.8
- its an AF 300/2.8
- its an AF 420/4
- its an AF 600/5.6300/4
- its an AF 450/4
- its an AF 630/5.6300/2.8
- its an AF 450/2.8
- its an AF 630/4
- its an AF 900/5.6
Sure 300/2.8 is different money! But I would be considering only the 200/2.8 or 400/4.5
Depends what you want it for. The 200/2.8 is quite a bit smaller than the 300/4 (lots smaller than the 300/2.8