This is a big deal for me, as a Daz/Poser user as well...having the Environment lighting included on the Shadow pass for Cycles.  The downside to not having this is having to include normal lights to create shadows that match the environment, onto a shadow catcher...which is not as easy as it sounds.

There is a "ticket" for this, that turned into a "Todo".  If you would like this as well, feel free to voice your support  :)

https://developer.blender.org/T34272

I'd like to think that there is a workaround for this. I think that rendering an AO pass in this situation would help. I understand that that isn't the exactly the same, however.

It is better to do one thing well, than to do many things and excel at nothing.

The AO pass is referenced on the original report, but if you can think up a good workaround, let me know.  There ARE workarounds that I googled, but they were not "simple"...

There is script that may be of use, it is called "Sun Position".  It helps to bind a sun object to a HDR environment image.  I haven't used it myself so other than this referral I can't be of anymore assistance.

Sun Position Script

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