As far as overall stats. go, barriers make no difference [as the number crunchers here will quickly tell you] with outside barriers winning almost as much as inside ones, but as far as I am concerned barriers are a track by track, distance by distance, horse by horse and even a jockey by jockey consideration.
A 1200m race at Ranwick is a totally different affair to the same distance at Caufield. Some tracks have an outside bias [Moonee Valley] others favor inside barriers [Canterbury] and depending on distance the bias may vary. It may all come out even in the wash but the individual differences are there to take note off.

Cheers.