One probe, one hdr camera, one shot, one crop and done (you've got the wife already ?) ?
image taken from http://www.pearsonfaces.com/fpsurgeon/labels/HDRI.html
Sorry Doug, you're the one
I know this method is used a lot, but I personally have issues with it. I'm pretty sure that the reflection captured in the sphere does not cover the full 360 degrees, also most of the 'behind' information is compressed into the very edges of the sphere and hence you'll lose resolution in those areas.
Basically, what I'm saying is that I can't see how this method adequately 'samples' the scene behind the sphere. Resolution to the front, however would be acceptable.