I've done both with no problems. Although I need to run it from the desktop because of having 2 monitors and TOR unlike other games does not lock the mouse to the monitor it's on. So I have to use a cursor lock program that made a special start icon for TOR on the desktop. But running from the Metro didn't have a problem outside of the cursor not being locked.
BW, this is the end of 2012. Join us from the 90's when people only had 1 monitor on their computers.
Did you done other tweaking on SWTOR or Windows 8?