Negative CrossFire™ scaling on "Final Fantasy-XIV" no longer occurs
Looks like Crossfire support for open beta has been added and performance problems with 3x and higher Crossfire has been addressed.
Final Fantasy XI 12-14-11 Update wrote:
Adjust the resolution of menus. The main screen resolution for "FINAL FANTASY XI" is dependent on the "Overlay Graphics Resolution" setting. If the Overlay Graphics Resolution is set higher than the Menu Resolution, menus will be automatically resized.