To be honest, I wouldn't be too worried about raw scores/bands for SJT. Bands are still a good indicator of how well you are going, and if the UK version is cheaper, then there won't be much to gain from paying more to switch to the Aus version. The raw score doesn't matter too much for SJT compared to the other sections, as it is not part of the percentile, but if you want to apply to a uni that takes SJT into consideration, then that's different. I wouldn't pay extra to see my SJT scores scaled, bands work fine (personally).