When playing the game on a multiple monitor fullscreen setup (mine is 3x Full HD = 5760x1080 resolution) most things are fine and are in fact great, apart from one class of text:

The yellow "pop up" type text such as

FATE Joined
FATE Completed
Quest Accepted
Quest Completed
X Unlocked

these appear stretched across the 3 monitors, and are thus very large and pixellated. (not to mention blocking the view for several seconds)
What it looks like is that the "text box" for this type of text is programmed to start X pixels from the left and end X pixels from the right, and then scale accordingly. This is fine for normal 16:9, but in tripple monitor setup it is horrendous.

There is plenty of other stuff that handles tripple monitor just fine though. Cutscenes are nicely centered on the middle one, even other pop-up text appears nicely centered in the middle one (as if that were the only monitor). So the code is "there", just needs to be applied to that type of graphic as well.

Steps:
1. Have a tripple monitor setup
2. Configure them in spanned mode to create a single 5760 x 1080 desktop
3. Launch FFXIV and set resolution to 5760 x 1080
4. For easiest demonstration of the effect, just go join any FATE and observe the "FATE Joined" text.

PC Specs
-=-=-=-=- System Information -=-=-=-=-
SYSTEM_OS Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.130828-1532)
SYSTEM_CPU AMD Phenom(tm) II X6 1055T Processor (6 CPUs), ~2.8GHz
SYSTEM_CORE_NUM SYSTEM_CORE_LOGIC 6 SYSTEM_CORE_PHYSICS 6
SYSTEM_BIOS Default System BIOS
SYSTEM_LANGUAGE Nederlands (Regional Setting: Nederlands)
SYSTEM_MEMORY 16383.133MB
SYSTEM_VIRTUAL_MEMORY 2047.875MB
SYSTEM_PAGE_FILE 32764.445MB
SYSTEM_DIRECTX_VERSION DirectX 11
SYSTEM_GRAPHICS AMD Radeon HD 6900 Series
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY1
SYSTEM_GRAPHICS_CHIP AMD Radeon Graphics Processor (0x6719)
SYSTEM_GRAPHICS_MAKER Advanced Micro Devices, Inc.
SYSTEM_GRAPHICS_VRAM 2027.672 MB
SYSTEM_GRAPHICS_SHARED_VRAM 2068.266 MB
SYSTEM_GRAPHICS_DAC Internal DAC(400MHz)
SYSTEM_GRAPHICS_DISPLAY_MODE 5760 x 1080 (32 bit) (60Hz)
SYSTEM_GRAPHICS_DRIVER aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
SYSTEM_GRAPHICS_DRIVER_VERSION 8.17.0010.1247
SYSTEM_GRAPHICS_DRIVER_DATE 6/12/2013 23:01:52
SYSTEM_GRAPHICS_DRIVER_LANGUAGE English
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_SOUND Speakers (ASUS Xonar D2 Audio Device)
SYSTEM_SOUND_DEVICE_ID {645D8EE1-E651-4279-B78C-02CFF97C5A82}
SYSTEM_SOUND_DEVICE_NAME cmudaxp.sys
SYSTEM_SOUND_DRIVER_VERSION 5.12.0001.0008
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 3/10/2012 16:43:46
SYSTEM_SOUND Speakers (ASUS Xonar D2 Converter)
SYSTEM_SOUND_DEVICE_ID {15912625-3F3F-493D-BFB3-8A416EDCD0DD}
SYSTEM_SOUND_DEVICE_NAME cmudaxp.sys
SYSTEM_SOUND_DRIVER_VERSION 5.12.0001.0008
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 3/10/2012 16:43:46
SYSTEM_SOUND Digital Output (ASUS Xonar D2 Audio Device)
SYSTEM_SOUND_DEVICE_ID {E60E2C32-82FF-4EA4-8E3B-4A62F76E7DED}
SYSTEM_SOUND_DEVICE_NAME cmudaxp.sys
SYSTEM_SOUND_DRIVER_VERSION 5.12.0001.0008
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 3/10/2012 16:43:46
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-