Can't talk specifically to the SVT Focus, but we've had the SVT COntour for 6 years now, and have been quite happy in general. These cars didn't get the press they should have, and I think that's why they are a little unknown.
I would go with the SVT version, even against the premium fuel issue, because you get a 6 speed to go with it, as well as more power, and better brakes. When you need them, you can never have enough braking. The price differnetial doesn't seem that big, especially if you option up a base Focus to the SVT level.
Carl