I have to admit, I keep reading comments like
"50 to 60hz is going to stutter" or "thats going to be jerky" and I can promise everyone here of the use that I have had with mine on vairious Amiga models that is doesn't stutter or jerk in any fashion.
I have tested it considerably with my 19" CRT / 42" Plasma and 17" LCD and if I could say anything bad is that colours looked a little washed on the LCD, but I believe thats more the LCD than adapter.
While I mention it, there is VERY subtle banding on the AGA machines I tested it with -
There are no slow-downs / tearing, stutters or jerks when using the device - I have tried Project X, Super Frog, DooM, Quake - from 68000 to 68060 - there are none of these problems associated with 50 to 60 Hz output.