Hey Walnut,
I had a very similar problem - personally I would get a remark because you don't know...I did extensive research and practice myself for over 4 months beforehand, and my best section, probably like you, was section 2 in this prep. However in the test it was my worst. I received a terrible %ile as well, although in general people will often do worse than they expect in this section. If I were you - remark! What have you got to lose? If it's the make-or-break of a medical career, $85 is a worthwhile investment.
No prep mimics Section 2 well. At all. Even the prac ACER papers aren't a true representation (they are easier in my opinion).