Well the non-polarized electrolytic caps are looked upon as lower quality then the polypropylene ones. However running them in parallel like that gives the cost savings of the NPE and any detail that might be lost through the NPE is passed by the poly. I would take a guess and say in a blind test you would not be able to identify which is which.
Edit: Guess I am a little too late with that explanation.
Yes still 6dB, so go from -13dB on the CD filter to -7dB.