Regarding the 50hz-60hz thing, I feel like I need to throw in my experience with this. My laptop supports 50hz and 60hz display refresh rate, by some twist of fate. I didn't choose it that way, it's just luck.
If I start up winuae on a 60hz screen, it's not bad at all. The scrolling on Turrican 2 looks quite smooth, it certainly is very playable. If I didn't know otherwise I'd say this was fine.
But when I switch the screen to 50hz the difference is apparent, it is silky, silky smooth. 50 frames in 50hz is like a stroking a warm fluffy kitten, and 50 frames in 60hz is like being clawed by a mangy old tom cat.
Anyway I haven't seen one of these gonbes boards in action - maybe it does a really nice job with the conversion and with a bit of scaling blur and standard LCD blur to hide it it's not noticeable.