As an owner of a Pro-610 for close to two years I'd like to suggest you guys are locked on nuts.
The TV receives a regular diet of two separate progressive sources (perhaps an X-box as a third):
1. Dish6000. While viewing Showtime or HBO or any HD-OTA channel the 610 correctly displays the progressive picture in full mode. The 6000 does allow changing the aspect mode but I find 'normal' to be just fine.
2. Panasonic RP-91. No explanation necessary. If you don't know about this player then do some research.
Regarding non-progressive SD material. You've owned the finest RPTV progressive display for a while now... You should be ashamed of yourself for feeding your set this antiquated garbage

. What are you thinking about?