Why did NEC not make the PAL system work correctly with the CD attachment?
The Turbo Grafx unit would have been modified to run at 50Hz rather than 60Hz, meaning the games run slower. Same deal with the Megadrive and SNES over here. The only reason this should really matter is when you're expecting sound to sync from the CD as far as I can see.
People flipping love Duos on here, but I don't own many CD games, I'm mostly about Hu Cards. There are some great CD games, but you can be content with what you have for years before upgrading.