Well i'm no expert compared to you thats for sure!!!
All i know is what i've seen, basically the disc (Underneath) appears to have two different silver dyes. The one around the inner rim (Ie, the wobble etc) looks very much like any other normal disc.
However, the rest of the disc is a different silver dye (and contains around 10+ different rings. (the best way to describe this is if you have seen a cdExtra cd (Basically a music cd which has data following it) it looks as if it has over ten various different sessions.
I've certainly never come across anything like them before.
The top of the disc is pressed using some cheap ...i'm guessing heat technique. This was scratched away thanks to some stupid mates who don't look after discs! and underneath it looked like a dvdregionx disc (although i don't wanna take much more off incase the dye falls apart when in the ps2.
When inserted into a pcdvdrom drive it reads as a dvdregionx disc and the files appear to be exactly the same (Although i need to confirm this)
As i've said before i'm sending you down a couple charlie for testing, Check you're emails a month back for the info.
Jay