I'm using it both ways, with PCB's (Raiden Fighters and Tekken 2b) and a Mame box.
For the mame box, I'm using linux + matrox G200 (excellent video card) + JPAC. It took me a bit of time to set it up as I was pretty new to linux but since, no problem, it's rock stable.
Shimmering appears on any bright pictures PCB or MAME (e.g. Asterix).