Just got my M3 DS Real Perfect package today and Kingston 4GB Japan card. It's a CP2 I'm guessing as thats what it says on the little bit of PCB sticking out near the contacts, only tried a few games so far but no problems yet.
Try Castlevania - Dawn of Sorrow and at the main menu wait 10 seconds or so for the intro video to play.
Tell me if it looks smooth or like a slideshow.