I can't speak from personal experience but from what I've read/seen, there's no point in forking out dollars for one of those cheapo converters, especially for use with the consoles you've listed. You might as well just hook them up via their regular composite output.
A better option, assuming your TV is capable, would be to connect via component. All the consoles barring 2 of the ones you listed output a native RGB signal, so all you would need is the appropriate SCART cable for each console and an RGB to YUV encoder, such as the CSY-2100 or any one of its clones.