^^ Those are my thoughts exactly.
AWD can be great in the correct application. But it needs higher power levels than what the Fiesta ST is providing to be worth the added expenses.
IIRC the 1/4 mile times for a stock first gen DSM (Talon TSi, Eclipse GSX, Laser RS) are nearly identical for the FWD and AWD verisons. AWD gets off the line fast, but FWD catches it by the end. Not sure how the two versions perform on autocross tracks, but I wouldn't be surprised to see the FWD being quicker.
Those cars have similar power levels to the Fiesta ST btw, but are a tad heavier (AWD is even heavier, obviously).
Mine: 2008 Saab 9-3 Aero SportCombi XWD: 82k, Black, MANUAL
Gone: 2002 SVT, #1654
Hers: 2010 Focus SES: 70k, Ebony, Auto, Moon and Tune