I will suggest to use ray-traced shadows only with spot and point light and  depth-mapped shadows with Infinite light only.. most of the users use the REUSE function and forget to clean it up after that why in some cases the shadows looks not accurate...

I use AO in my HDR IBL and it works very well, the value is very low, when working together with the extra light the AO doing own thing on the best.. react also to the extra light and show only in the places where the extra light don't hit the surface, as it works in real world..it is fast and accurate

I use only depth-mapped shadows for the extra light when the base is HDR IBL.. ray-traced shadows are sharp as well and represent the shadows when the light coming from objects like lamp and spots.. ( not infinite light ) you can blur the edges as well or set the intensity a little bit down..

I tested the depth-mapped shadows with the HDR but this don't work very well, even if you change the shadow value to 300 it looks better but still it is not good and the function don't works as you think it would works.. HDR is nothing else as only Global Illumination there are not shadows beside Ambient Occlusion, you should use one more extra light for the specular and shadows.
For example if you put in real life a white plane in front of you the light that reflect from that  would not create a shadows behind you right? it is not strong enough.. so this make a sense..
Use HDR IBL light as a base lighting only...

The best ratio for that is setting the HDR IBL to 65 % and the extra light intensity to max 35 %, this way you will get 100% light intensity and you don't have to change the Diffuse Color however this way don't give the best effect.
Other thing here is that the poser scene is very small , only 7% is lighted up from the HDR IBL Light-probe, you should change also the Image Resolution to 7 in the material room to have more accurate and well the best light for now...
However when Poser8 will have GI , it will make it not so simple to get the realistic effect,  you will have to compose a complete scene with all right materials and textures that will generate around the model the right Light..and the rendering time would be also very long.. HDR IBL is the most simple way to capture it with one simple light and I love the simple way :) Simple is beautiful!

Cath

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"Surrender to what it is - Let go of what was - Have faith in what will be "