Hey guys,
Good discussion! One thing to keep in mind is that
the Official Guide only contains questions that have been retired, and I remember hearing that the rule was that the questions had to have been retired for 5 years before they can be published. Even if not, by the time the questions are retired, provided with solutions, formatted, edited, and published you're looking at questions that haven't been live GMAT questions for a while, so you're looking at the historical GMAT in the
OG.
The test has to evolve, and GMAC takes that responsibility quite seriously by researching each potential question thoroughly before it ever affects your score. So the current 700+ level questions are almost necessarily a little different from those in the
OG - they have to find ways to trick the top 5% of test-takers, many of whom have breezed through the
OG as you said.
Particularly on the math side, there's a ton of value in seeing what GMAT experts are writing as new questions, as we tend to take the concepts that we've seen on hard official questions and ask "how could they make that harder?" or at least "how could they ask that differently?". To prepare for a 700+ score, I'd certainly recommend:
1) Devour those new questions in the forums
2) As you see new questions, do what we do and ask how you could tweak the question slightly to make it harder or elicit a different answer; that way you'll be more flexible in your problem solving and abilities with those concepts.