I too can vouch for the 1.2. I bought mine 7 weeks ago after a short test drive. I have to admit that I was a little disappointed with the performance of the engine, but as it was being bought as a second car and this one was available to buy straight away.
Now, with 1200 miles under its belt, it feels so different to when I test drove it with just 10 miles on the clock. Upon delivery 4th and 5th gear were unusable for ANY acceleration , now whilst not exactly neck snapping, progress can be made without so much gear changing but when you do, it really surprises me and other road users how well it goes, AND its so smooth when when doing it.
Economy wise, the total average for this period is 43MPG ,(according to the relatively accurate gauge that I checked against proper figures for the first couple of tankfuls). This is mostly London driving with a few longer runs as well.
In light of the premium charged for the other two motors, I would certainly give the 1.2 a test drive, just try to find one with some reasonable mileage on it!