The below is a verbatim comment from the Manhattan GRE Blog :-
750-800 Math estimates can end up all over the place – 750-800 was the best quant estimate that you could get on the revised GRE, but today that range can mean a score as low as the 85 percentile (based on scores we have heard so far). The fact that a range of 6 score values on the old test (750, 760, 770, 780, 790, 800) translates to at least 10 different score values on the new test (162, 163, 163, 164, 165, 166, 167, 168, 169, 170) shows just how out of whack the old quant scale was. Unfortunately, it also means that receiving a 750-800 estimate on your quant doesn’t tell you much about what your official score will actually be.
Did anybody else receive the revised GRE score report ?