n900 and n9 dsp are almost the same(just higher clock on n9), n9 barely plays 720p and you wont get more than that because it is a physical limitation of the chip, not a software one

you can only hope that a software update will enable you to finally play all 720p videos perfectly, althou i wouldnt hold my breath

and 701 plays everything right now, you dont have to hope for a better future that might not be there