The default firmware does a terrible job and incorrectly displays the signal as 480i, so games that have blinking every other frame (such as Strider on Genesis) instead show a striped object. Here is an example of a blinking object appearing as striped (no it is not scanlines): http://tinypic.com/view.php?pic=33otced ... 2qmWHnD_0w
There are expensive upconverters that I could buy to do what I want, but a custom firmware should theoretically be able to do the job. Here are examples: http://retrogaming.hazard-city.de
I was also wondering if SamyGo allowed the VGA input to display 15KHz signals correctly, many RGB outputs from console games use 15KHz and it does not display on stock firmware. Odd because my Samsung VGA LCD monitor displays it fine.