I suspect that the law of diminishing return now applies to the 770, and that investing substantial amounts of time in order to squeeze out a slight performance improvement that is specific to the 770 platform is probably not worthwhile, however improvements that benefit both platforms is most certainly worthwhile.

I wouldn't say that 770 specific improvements should not appear in mplayer, just that any such improvements may benefit less users than if the same time were invested in improving performance on the N800.

My view is that the 770 is limited by it's CPU rather than the graphics subsystem, whereas with the N800 it's the exact opposite - good CPU but a poor graphics subsystem. Thus there is more scope for tuning on the N800 than the 770.

As a media platform the N800 wins hands down - 16GB+ of potential storage compared to the 770s maximum 2GB for starters!