I always thought these were interesting and wished there were more so here's mine. I took the exam yesterday
Manhattan CAT #1: 650 (Q40, V39) 5/10
Manhattan CAT #2: 670 (Q39, V42) 5/18
Manhattan CAT #3: 700 (Q44, V40) 5/24
Manhattan CAT #4: 700 (Q43, V42) 6/5 (this was also the first time I did the essay and IR all the way though)
GMAT Prep #1: 720 (Q44, V44) 6/14
Manhattan CAT #5: 740 (Q46, V45) 6/21
Manhattan CAT #6: 730 (Q45, V45) 6/27
GMAT Prep #2: 730 (Q46, V44) 7/5
Real Test: 760 (Q47. V47) 7/10 8 on IR
So there it is! In terms of accuracy, my GMAT Prep results and Manhattan results pretty much fit in with each other in terms of scores. In terms of actual questions, there is no doubt in my mind that Manhattan Math questions are more difficult than the real questions. However, scoring differences may ultimately get you to the same place. Same goes for integrated reasoning; the Manhattan questions were more time consuming. I do think I could have performed a bit better on Math, but given that I got 20 points higher than my best practice and that I'm in the 99th percentile, I obviously accepted my score and will not retake.