I know the Fiesta ST is a performance model and not everyone is looking for that, but in my opinion (being that I work for Ford), if you can swing the extra money, it's the one to get.
It's fantastic and offers so much more for the extra cash.
I agree that is not always a bad idea to get the performance model. My dad used to buy the Taurus with the OHV 3.0 and that makes a ford tortoise. Then he drove one with a DOHC and now he wont buy it unless it has a DOHC. He likes the extra power and the power makes it more comfortable to drive.
The OHV would feel a huge OOOOOOFFF in the power with the a/c on and it was not comfortable to keep downshifting on the highway just to keep up with traffic. The DOHC can have the a/c full blast and it handles it and still keeps up with traffic and everything, its great
surprisingly the DOHC is actually easier to work on ...I had to change the a/c compressor and I got it through the front by loosening the mounts and rotating the engine with a ratchet strap.