Hey there, I don't do PD/H/PE though I can provide information for Economics once you reach HSC level.
Economics is quite a rigorous course and that's reflected in its favourable scaling once you reach the higher ends. However, the standard needed for achieve a b6 is quite high, so the aligning for Economics throughout the years has less favourable than its social science counterparts (the standard of getting a b6 in PD/H/PE is high as well, though still a bit more favourable than Eco as previous data suggests). Based on the data UAC has given us 5% of PD/H/PE students received b6 while 12% received a b6 in Economics. (keep in mind that this stat is greatly influenced by the amount of academically strong students that choose Economics due to its high scaling as well as the cohort of PD being nearly 3x the size of Eco)
In terms of content, I feel as though my current knowledge of the prelim course is a bit hazy, so I might leave that for someone else. I dicussed something similar in another thread:
The only con I can think about in picking Eco is that it is packed with a lot of content and it'd be hard to get through it all unless you have a degree of interest in the subject.
IMO, despite having lots of content I really enjoyed studying Economics and
I feel that my understanding of the world of economics (as corny as this sounds) has broadened as a result. Although I never achieved my primary goal of picking Eco (back in my naive days a greatly influencing factor of my choice of eco was that I thought I'd learn how to invest in shares LOL).
I'd recommend Economics anybody willing to put in the extra effort to excel in the course, it's definitely worth it and you'll learn a thing or two here and there which you will be able to apply irl in the future. (though my view is a bit biased since I didn't do PD/H/PE)