I've stumbled across something rather odd.  
 
I've set up a 360 shot in a small alley.  First disclosure...my tripod head was miscalculated, so I wasn't expecting much since I realized 1/2 way through I'd set it off by just a bit.  
 
I finished and processed the images, and was able to get surprisingly good output from the photos using a center weighted spherical rendering.  When I exported cubic, it was _terrible_ ... as bad as I was expecting originally.  So I re-exported full scene as spherical, and the irregularities creep back in
 
How is this possible to get such vastly different results?  
 
In my first spherical render, I cropped out the top 1/4 and bottom 1/4...so in the files at the link below, the 'Spherical' is resized, but was cropped only on the horizontal FOV...its original height was set to the same vFOV as seen in the photo.  
 
The 'Cubic' image is the corresponding cubic face
 
The 'Full' image shows the whole panorama when rendered spherical, which has similar blurryness to the cubic one.  
 
So...again, knowing that my source is botched, why was I still able to get such a high quality spherical?  Look at the flower pot or the flag...they're unblemished, but in the full renders, they look awful.
 
Thoughts?
 
http://gfstop.com/files/
 

Hi,
actually the reason could come from the blending.
In Spherical or Cylindrical you have the smart blending available which will correct the artefacts. In cubical there is no smart blending that's why the render could be bad. Can you check it in the window rendering options ?
 
regards
Autodesk support
 

On the 'full' version thats there at the same link, it was a spherical render, and it also exhibits some of the issues as seen in cubical.  Typically my approach was to render to spherical and then convert the panorama to cubic after the fact.  
 
I suppose what surprised me the most was that:
 
Spherical center weighted 360 degree strip: virtually no ghosting
Spherical full up and down pano: ghosting, especially on upper and lower edge
Cubical full render: massive ghosting
 
If I'd taken it correctly the first time, this would not have been any issue, but I am surprised at how well the center weighted strip rendered, but confused by how that varies depending on how much UP and DOWN I introduce.  There was one shot series taken a 0degrees, one at + 60 and one at -60, and then straight up and down.