The key fob attack is superior since no one looks twice if you walk up to a car, it unlocks from a hand held device and then you get in and drive off.
<EDIT> Seems HN has different experiences with their cars then my own, So I'll concede the idea that the alarm doesn't trip when using the key. It seems the cars I've had in the past are the exception to the rule. </EDIT>
The thing is, in the real world, no one really looks twice when someone gets into a car unless they are using obvious brute force to get into the car.
(One day, when I can be arsed, I'll rekey the car and reprogram it with fresh transponders, but today is not that day!)
But "reprogramming" a key (more like adding a key) on that model of ford just involves doing a dance with the fob key then inserting the key with the new transponder. So we plan to get all keys working on the car at some point. I was just going to order a new chip but my bother was complaining about the key barrel being a bit loose on him so just doing to replace everything at some point. Its just more about not being lazy about it :-P
Thing is, its what we call "the work horse" car of the family, it gets used about once a week to do tasks no one wants to do in their own cars (or when I need to do something in a car), so its not really a high priority thing to fix, but if we are going fix it might as well do it "right")
And in either case you still need to deal with the immobilizer, and turn the core of the ignition lock. Unless your radio device is that comprehensive :)
So that attack when done on its own is mainly left to stealing cars off drives at night rather than say from a supermarkets car park during the day.