I've been hearing "fixes are coming in the next version" for six months now and I haven't seen much improvement yet TBH.
It's kind of embarrassing because Linux was supposed to be the lean and efficient version of an OS. Well I guess that was true under GNOME2 but I don't know what the hell is going on these days; it's a huge mess and I wouldn't advise any newcomers to dip their toes into this pool.
If Xrender extension was improved to support vsync, we would not need opengl compositors that need substantial gpu power to work right.
I'm using Xubuntu 12.10 and xfwm4 is very light and good looking, problem is the tearing because the lack of vsync in all xrender compositors.
X is outdated, there's nothing Valve can do about it.