The slightly older US date code that was in impeccable condition.
I too thinking about 400 f2.8 IS version I. Would be nice to have version II, but the price tag is little too high for me.
I bought a S/H near mint 400 f2.8 L IS mkI last year, just before the mkII's were released. I figured that I won't loose money on it and if I need to I can upgrade to the mkII as and when. The 400L is everything people are saying....it's AF is fast and very accurate. It's jaw droppingly sharp....it's one of the few lenses which can be used with a 2x TC wide open. It's very versatile too, the ability to use TC's really expands the use of this lens. It becomes a 400/2.8 a 560/f4 or 800/5.6. The only problem with it is it's physical weight....it's REALLY heavy and cumbersome.
There are lighter ways to shoot wildlife!
If I had a clean slate and 10K to blow, I would buy the new 500IIL. It's SO light and easy to handle. I'd loose the f2.8 option but the rest of the package really makes up for it.
Thanks GMCPhotographics for your feedback,
The reason I want f2.8 in telephoto lens, because my daughter is taking indoor swimming and ballet. Both activities are indoor, therefore, f4 or f5.6 might not be fast enough. My shutter speed usually some where 1/250 to 500ish.
I don't mind the weight of version I, since most likely shooting will be on tripod/monopod. The photo below was taken with 70-200 @ 200mm. I cropped nearly 60% through LR4. I'm not sure 300mm is long enough?, but it's nice to be able to shoot handheld