When you hear all this debate about IS vs non IS, the original (ver I) of the EF 70-200 f/2.8L IS is one of those lenses that exhibits the 'turn off IS' internet advice this is now mistakenly and universally applied to all lenses. The original (ver I) does not have the technology to detect a tripod. You'd be better without IS or the vII or vIII IS models.

Regarding a Japan (non N America) source, why? All the many versions of the EF 70-200L zooms are widely popular. It seems virtually impossible a better deal cannot be had closer to home.

IMHO, an IS lens IS a requirement for wildlife, especially for b.i.f., so you are heading in the right direction. However, also my opinion, 200mm is the SHORT end for wildlife, so why not entertain a 100-400 or a 150-600? Reach is everything with wildlife, especially birds. Of course sticking with your camera's own lenses costs more, but the results will usually be better, but not always. Many of the third party lenses get very close to the camera manufacturers choices as far as image quality goes, however the native ones are typically winners in the focus speed and accuracy areas.

I see that your avatar is an image of the bird, so if you do a lot of shooting at 200mm and don’t need high SS for your subject, IS will allow you to shoot at a lower SS and ISO without camera shake (which can certainly occur with a 3Lb lens), which will lower noise and increase DR. It’s also useful when panning moving objects. There are multiple versions of this lens. In addition to the non IS version you have, there is an EF 70-200 f2.8L IS USM versions I, II and III with each IS version slightly higher performance and substantially higher price. I’d say the IS is a definite improvement, and which version you buy will depend n your budget. The version I is going for ~s800, the version II ~$1100, and the version III maybe $1400-1500 (all used prices)