Well my quant scores in practice tests ranged from 46 to 49. And my score in the real test was way below that in the practice tests.
Here is what i think - the real test is definitely tougher or rather trickier!! I actually felt fine while doing the test. There were some very easy questions and some very unusual questions!!! Respecting the confidentiality agreement, the weirdest question i came across was one which involved an Algorithm!!!! Never expected that but it was very easy with a very obvious trap!!!
The reason i think my scores dipped might be because (pls take this with a grain of salt) in the practice tests i think the level of difficulty hits a threshold and then it wont get any tougher but in the real test since the database of questions is much much bigger, the toughness of the questions has no limit until you start hitting the 50 or 51 range!!!
Hope that helped.
Here is one tip which i'm going to follow for my retake - Know the fundamentals absolutely well. One has to be fluent with the formulas, concepts, techniques etc because there is absolutely no time to spare in the test to actually sit and analyze the concept being tested. As soon as you see the question you should start solving not analyzing. For this you need to do 2 things - 1) Hone the concepts and fundamentals and 2)Practice, practice and then practice some more.
And as far as i remember i got only 1 combinatorics questions and it was extremely straighforward and easy. Number properties and Algebra were the lead players closely followed by inequalities. Geometry and coordinate geometry represented app. 3-4 questions.
Here is another tip: If you are planning to spend more time on the first 1o questions, then all i can say is that you are digging your own grave. I noticed one thing in both of my GMAT tests. There were a lot more word problems towards the end of the section 23-37 and these take a lot of time. So if you already are lagging in time then chances are that you are going to just randomly guess on the last 5 questions if you want to complete the section, and thus seriously hurting your score.
Hope that helped.