Keeping it stock or? I can say, turbo cars often times last about 100k before needing work done to the turbos, but they are fun. I've never driven a WRX, but I've been driving an 07 Outback since December, and I love it. The AWD on these Subaru's is absolutely amazing. We get tons of snow up here and it goes through it all (I have gotten stuck a few times, only needed to get pulled out once...).
The only thing is, gas mileage isn't too great. I got 25 mpg this past weekend with 4 people in my car cruising at 60mph. When I go 70-75, I get about 22-23mpg highway. It will be a few less in the WRX. So it won't be a huge improvement on your F150, but it will be faster.