while I didn't take the exam in 2016 (I took the exam in 2014), the real questions were already significantly longer than the questions in UWorld, however they more or less had the same content. They only stuff in some extra physical findings, lab values or history extras.
To prepare for the longer exams, try to finish each UWorld block with maybe 10min extra time left. If you are able to do that, you should also have no time problem during the real exam.
If your NBME scores are similar to your goal score, then you should take the exam. If they are low, then you should postpone it. Try to do those exams online and don't do those offline forms.