I'm suprised too, Last time I tried LoL though, I was running a slightly older ATI HD 5700 and ATI drivers on Linux are crappy anyway (Getting better attempting to keep up with Nvidia)
But LoL said "Hell No" Every step of the way.
This time, I installed, Updated, And went into a game (Created w/Bots) Sos as to not crash on a real game and get leaver status.
And did not have a single problem. (YET)
I should mention I only played 15 minutes, Bought items at the shop, Blew up a tower etc, No graphical Glitches, Silk smooth glossy constant 60FPS (Capped @ 60) just beautiful. We will see what happens with extended play and vs humans.
Nvidia 650 Ti 2 Gig