I found a thread over on EAB where somebody mentioned the OSSC does not convert 50Hz PAL to 60Hz NTSC. It just passes through whatever refresh rate the input signal has. I'm glad I found that before I bought an OSSC.
I've already got two games I can't play because they are PAL only. My A500 has an 8372A Agnus. There is an NTSC/PAL menu option on the ACA500+ boot screen. The only thing I need is a gadget that can translate PAL input signals for my American HDTV.