There might be others like me; I logged in and my screen began to flicker rapidly between the loading screen and my current position in the world. Rotating the camera would result in blurs of light across the already-flickering screen. The game is virtually unplayable like this.
The fix I found was to add the following to the Config.wtf file:
SET M2UsePixelShaders "0"
SET M2UseShaders "0"
SET ffxDeath "0"
SET ffxGlow "0"
I believe there are some config.wtf fix mentions in both the Tips & Tricks as well as the Wine HQ that use this configuration.
Just wanted to point out that flickering is also fixed by those modifications.