", I dislike certain proposals and design details of weston"
Same here, but that's OK: you don't have to use Weston .. Plasma 2 will still have KWin :)
"multiple copy buffers"
Possible with Wayland extensions
"first class network support"
we don't even have that anymore in practice with X11 since nearly all rendering is now client side. that said, Wayland will almost certainly get something very similar (though more rdesktop-ish)
"Sub-surfaces seem to solve the problem with video direct"
Yep .. lots of good evolution in wayland to resolve these kinds of hard issues.
"I think we'll see if it can complement or replace X11 properly in few years."
we all are :)