Hmm. I'd be interested to see the results of that (though if it showed that lard was better I wouldn't want too much publicity for it ;)).

My suspicion would be that chip shops that go out their way to use a cooking fat that's not the default standard also go out their way to cook the things properly - I think that proper temperature control and giving the things enough time are probably more of a factor, at least in terms of not giving pallid greasy squishy things.