I don't see how you can loose with this deal. As mentioned you can always upgrade the panel rather inexpensively and the frame is worth the hassle as a work of art on the wall ( I prefer the older frame as well except for the new 65").
SD content is going to look better on the 720p BV4 than the Full HD (and certainly better than LCD with SD), and trust me that you won't be missing a thing from any comfortable viewing distance with 720p@50" as the picture is absolutely fantastic.
I work with film and HD content for a living so I look at properly calibrated broadcast monitors all day long. It's true that the Avant is absolutely fantastic and I love it in the lounge but if it came between the Avant and the crowd pleasing, game watching BV4 in the living room the Avant would be gone in a heartbeat.
Forget the panel. You're getting one of the best Plasma/frame/speaker on the market and a video processor/master system that you can build your new house around.
If the panel gives you any issues... toss it for a brand new Panasonic that will be indistinguishable in the new frame.