Spun PP has been around for ages. It degrades quickly with exposure to UV and heat. It's almost impossible to use in a molded application due to the heat issue. I read about this in the composites world blurb, here
the recommendation is a cover layer of glass over graphics and my guess is the graphics are what offer the UV protection.
Spun PP offers better wet out than Extruded PP. I guess that I'm not sure what the advantage is if you're having to cover with a layer of glass anyway...I guess strength, but if you're using a 1 oz that you have to cover with something like 4 oz top and bottom and completely paint it, you've probably given up the weight advantage.
Interesting stuff, though.