They lost it when they started partnering with NVIDIA. Every Mac I've ever owned with NVIDIA has glitches. Every Mac I've ever owned with ATI has been rock solid.
I'm also having the occasional screen flicker to external display but only when using the 9400M & only when plugged in via VGA adapter, DVI works great.
Also, I discovered that, for some strange reason, when using the 9400M if I plug in my Polaroid LCD using VGA and then plug in my DVI monitor again the lid sensor stops being able to put my Mac to sleep. At first I thought this was a sensor issue until I tried to change graphics processors once after having this issue. It logged out, went to blue (like it does when switching normally), but then went back to aqua with mouse cursor, then back to blue. It does this over & over again but does finally go to login. When I login & open preferences, it has dedicated graphics selected now but has an exclamation saying I need to logout.
I know lid sensor is work as well because I can select sleep from the Apple menu & then when opening the lid it wakes up fine. Very strange.