In case anyone else is interested in the Fiesta, here's something you should know.
Well, I've had the opportunity to drive the Fiesta ST a few times now. And this is my verdict FWIW when comparing to the Titanium version.
(Example. I drove a black version which looks really cool, but gets really hot
First thing you'll notice is the significant advantage in accelration. It goes about 3 seconds faster from 0-100 KPH/0-60 mph than the Titanium (hence forward the 'T'). But it should too, because it has an extra app. 60 HP compared to the T 125HP version. The ST should make it at just over 6 seconds, but I believe it may be able to do better because I can do better than 9.3 with the T. Hard to tell, though because it's got to do with the following point.
Second thing is no turbo-lag. This is an obvious advantage on a track, but not necessarily so on the street or road. The point is sort of you can only go fast or slow in the ST because everything kicks in so quickly unless you fiddle a lot with the clutch and speeder. The T has a turbo lag that you can manipulate to get just enough of a lead at green light, but without exploding forward, which is rarely wise in a congested city. Besides I sort of like the lag that kind of sucks the car into speed after a second. If you plan it right and time it with a gearchange, it'll give some very satisfying results.
Third is the general driving feel. The Fiesta in all kinds of versions is allready a very dynamic driving experience, and the ST is of course no exception. I'd say though, that the slightly different suspension does not make a hughe difference on roads (maybe on tracks, dunno). High speed cornering seems a bit better, but I'm not sure how much that is due to the actual suspension, and how much is just the ST having more pulling power. Cornering through throttle is an effective option for both of them.
Fourth is the gearshifter in the ST (manual 6-speed). I've seen it praised as precise and sharp. I dunno, maybe it's just me, but I don't think its better. It's got a more metalic feel, but the distance betweeen gears are just as long as in the T. IMO they should have given it a short-shifter (you can get that from unoriginal suppliers). The softer shifter of the T (5-speed) does the same job just as great, but maybe wouldn't be up to the task with more HPs. Possibly not.
Lastly some more differences that are obviously better in the ST: better brakes, better looks, better seats.
The overall question is: Is the ST worth the app. extra 80% compared to the T? Well, I'm not sure tbh. Of course if money is not an issue, you just get the ST. But if you're trying to max your fun compared to money, I'd say the T is enough. It's got the same driving dynamics as the ST and if you mainly drive in urban areas, the ST is not going to give you that much extra for the money. Where the ST shines, is on the smaller, winding roads, but even here you can have fun with the T too.
Later this year, Ford is releasing an improved T in shape of the 'Black&Red' edition. That car gets an extra 15 HP plus some styling. It means there's going to be a middel-in-the-road for someone who fancys the sporty feel of the ST, but doesn't really have the option to use the full potential of the ST. I'd buy the Black&Red if I had to make a new purchase this year. I doubt that I would get full value for Money with the ST. Roads around here are too congested and speed limits are being lowered in most regions, making it very hard to find places to drive the ST as it deserves.
Another option for someone who thinks the Fiesta needs beefing up a Little, is to customise it. Well known companies like Mountune and Pumaspeed allready released various upgrades for as well the ST as the T. I honestly wouldn't know what to do with an ST at the top 250 HP, though. Considering the weight of this car, such power belongs on a track only, IMO. The T could use an extra 15 to 25 HP no problem, though. But the crazy app. 200 HP that some have crancked it up to, seems pretty hazardous? You'd then need disc brakes on all 4 Wheels, at least.