I cannot compare GMAT with OG as I never studied OG. But I think, PP is a close representation of your actual score. I got 540 on PP1 and 570 on PP2. I gave both within a week's time and also gave them without studying OG. So, I really don't know if PP will be an approximate representation of your GMAt score if you have given PP after studying OG. Verbal had SC, which were pretty long. 2-3 short sentences and rest were long. RC was not as boring as I had thought. They were interesting paragraphs and hence easy to answer. But, they were all long and hence I had to spend lot of time on them.
I hope this helps. All the best.