Other observations:

It makes no difference at all to the render where you position the light.
However, if your IBL lighting has a direction to it - as is the case with Aiko above, then you should put the light at an angle corresponding to the "Key" light in your IBL to get the preview to look right.

Important: IBL is based on world coordinates. The lights will work as expected only if your camera is straight on from the front.  Shoot from behind and they get reversed.

Well, that's all I remember for now - just hope I cleared some things up, and didn't just add to the general confusion that seems to surround this topic.

Rô

My favourite question is "Why?", my second favourite is "Why not?"