Well, I'm still waiting for a reply from the vendor, but it looks like "we" already know what the answer will be... no point in "converting" a composite or S-Video signal with an expensive box, since the SCART sockets are already switchable to take composite or S-Vid directly.
Btw Dan, thanks for your concern. I did in fact test whether running the video through my receiver would degrade the signal. Thankfully that does not appear to be a problem with this receiver. I agree with you whole-heartedly, and you can find several threads on this forum where I have recommended direct "source to monitor" video connections to others.
What looks interesting now is the box I initially paid little attention to, that will convert Component video to RGB. Since the Component signal is much better than S-Vid, it might be worth the expense to be able to watch DVDs at the "component via RGB" level on input1, while running S-Vid from the other sources directly into input2 (as I'm already doing :)