P16 stands for Problematic 16. Which means this disc would be problematic to burn at 16x (I'm serious here )
But why sell them as RIDISC extreme which is E-net premium Ritek brand that's supposed to be a real A-grade product.
Also traxdata has give some places samples (Cdfreaks for instance. Pioneer 109D ->4x in there review ! )
But there's hope according to my latest info quite some new firmwares allow it now to burn at 8x or 12x don't know if pioneer fixed it.
R05 I have seen on Philips site however I have reasons to doubt that we really will see this one on the market. Remember the famous G06 ! (It exists and was going to replace G05 that was untill G05 got much better support and some component prices dropt which made continueing with G05 a better option.