The Quadscan or an HTPC would be my choice with the HTPC being first choice. I know is wasn't in your list of choices. The Ican can only do 480p and with a 90" wide screen scan lines will be very obvious. Any double or scaler would be much better than SVideo. I am using a HTPC with a BG800 and I get a film like look from 5 feet back from the screen.
Mike
Mike