I know what you mean, regarding the SVT "taste," and that is a lot to be paying for a non-SVT Mustang. There is something about having the absolute top of the line within a model range, and you would get that with the SVT.
Get quotes for insurance - my 5-door is $867/year...and my wife's 2000 Passat GLS wagon is $627 for the identical insurance. In other words, the SVT will probably be lower than that GT, but maybe not all that much lower.
Gas may not be that different a story - expect 30 mpg in the SVT if your daily commute is highway. I bet you're getting 25 in the GT, under similar conditions, so again, maybe not that much of a savings. Also, there is the fact that from the factory, a 2002 GT runs on regular - don't know about yours. SVT Focus needs 91 octane.
Most important is the fact that they're completely different cars - what the Mustang does well, the SVT does less well (acceleration numbers, low-end torque, RWD characteristics), and vice versa (real room and real access in the back - esp. 5-door, overall better and more sophisticated handling, better high-rpm performance, more up-to-date car).
Just make sure you want to make that big a switch before diving in. Now is the time, though, especially if you can find a 2003 model.