BD9: 720p vs 1080p

[mike_tee_vee]

In general terms, when backing up a BD50 to a BD9, would the subjective picture quality be higher at 720p or 1080p?

1080p would obviously have more resolution, however in theory the 720p conversion should have more data per pixel. Can anyone confirm if this makes a difference?

[signals]

I think this is a subjective choice. I prefer BD-9/1080, but my notebook has a 1920x1080 screen. They both look very good to me.

[big_moviefreak]

Signals if your equipment only supports 720p is there any benefit to backing up bd to bd9 at 720p or is there really no benefit?