I have the DV971H. There's an option to set the player to widescreen for widescreen content and to leave alone 4:3 instead of stretching it...the option is called "Wide/SQZ" in the menu, but then again my TV doesn't take the initiative to stretch 4:3 on it's own. It's an Olevia.
I'm not sure how the Oppo transmits the squeezed 4:3 to the TV. If it sends it with a widescreen flag by adding the black side borders your TV might not stretch it. But if it sends it as 4:3 and expects your TV to play nice it might be a problem.
The catch with the 971H is it only supports upscaling through the DVI, which also supports interlaced resolutions in NTSC and PAL formats. If you use its component outputs you'd only get 480i.
It's a nice player. You CAN change the DVI output setting from the remote, BUT you'd have to press the stop button on the remote first (unless it's already been stopped). You can't change it while it's playing a movie unfortunately.
Oppo's recent line of players are a major upgrade, but I don't know much about them yet. They seem really good, especially the black one. If you're interested in any of them you can get more info on
www.oppodigital.com