We use weights that make the profiles/speeds as similar as possible and the 767 is in fact more stable and easier to fly than the 737. The briefing lasts an hour and no question is too stupid - really you will enjoy getting your hands on a big aircraft. As for the Compass, we are new to it too and will be looking for a reliable correlation between those results and the sim assessments. I did the tests myself - but no-one will show me the result!
Forgot to add - depending on your experience, might get you to fly a hold or two asymmetric so that you can see how it feels..
SKB