I did. I traded in my Fiesta ST to get the VN with PP. I hated trading in the ST, but I didn't want to have two cars which essentially performed the same function. The Fiesta ST was awesome fun, but overall I like the VN better.
These are my thoughts on the two:
To me, the VN looks a lot better than the ST. Although I had the orange ST with black wheels, I really bought the ST because of how it felt to drive, not its looks. I've got the Performance Blue VN, and it is definitely a better looking car. I do wish it was either a true two door or a four door though, but that isn't a big deal and (to me) doesn't affect the looks of the car.
Both are good, but I think the ST had a smoother-shifting manual than the VN. The VN seems a bit notchier and takes a little longer to shift. Not bad though. Both cars have really good transmissions.
Both are very good. The VN does feel a little heavier than the ST, but both are very immediate and very fun. And wow, the VN sure is flat around corners! Also, I've already done an autocross session and a road course track day in the VN, which I avoided doing in the ST, even though they are popular cars at least for autocross. The reason is that the ST seemed to me a little too similar to my previous Fiat 500 Abarth, which I enjoyed very much but which rolled over very easily the one time I ever slid off a road course into soft earth. That ended the Abarth. Also, the brakes on the ST felt very good but I didn't have confidence that they would do well over persistent heavy braking on a track day. The VN had absolutely no problems on my track day.
I really love all the extras on the VN. What a car! I love the shift lights and the selectable suspension. And the muffler system is fantastic. The ST doesn't even approach the sound. It sounded pretty bland. My former Abarth sounded great, but I don't think it sounded better than the VN, which is saying alot.
I really enjoyed the Fiesta ST. The only real objection I had about that car was that I think it had the worst front window defroster of any car I ever had. Other than that, it was a really good car and alot of fun. It also had slightly more practicality with four doors, and weighed a couple hundred lbs less than the VN, which is always good. But the VN is better and as much or more fun. Actually, I'd recommend either car to anybody who asked.