so, after further testing, it works now
didn't tested komponent so far, but hdmi input works great.
had to set a new composition with 1920x1080, then the source also got this resolution (720p won't work, otherwise 640x480 or 720x576 resolutions work).
delay also seems okay, further test will show if it runs smooth also, but looks good now!
i'm really impressed of this cheap video capture device.
okay, it's not a blackmagic or matrox and only runs on windows so far, but i can even use 2 sources simultaneously (svideo/video or komponent/hdmi).
MainSys: Z77 UP5,3570K,32GB Ram,GTX 285, M3 128GB,4x3TB R5@LSI9750
VJSys 1: 990FX UD5,X6 1045T,16GB Ram,GTX970+610+610,M3 128GB,3x1TB R0
MBP 3.1; Schenker A102 (650m) & P702 (675m)