I took my GMAT today and got 750 (Q51 , V40, AWA 5.5). Not sure if I should feel good since I have been scoring >770 range in past few weeks .. on the other hand the score is good enough that I might not have to take the exam again.
Mock CAT scores
GMAT Prep 1 : 720 (first time, almost 2 years back)
GMAT Prep 1, 2 recently 770
MGMAT CAT, 760, 750, 780, 770 etc..
Advice : If you are getting a good score ~720-760 on GMAT prep and other tests than do not waste too much time studying and pick a date for your test. To get a score above 740 is more of luck, than of hard work.