I'm not convinced it's worth the expense of an LPG conversion given the good economy to start with. What you need to think of is how many miles you'd need to do to recoup the cost of the conversion. As both do around 45mpg is it worth it really? Also consider what your annual mileage is.
I would guess that unless you are doing a stupid amount of mileage each year it's probably not worth it.
I agree with this. I worked out if I got a Multijet Panda it would take me 10 years motoring to get the difference between a 1.2 and a Multijet back !
So basically it would take me 10 years before I started saving money on fuel !