I think the GRE is basically used as it should be: to cull poor applications. Given that you can rewrite the GRE to get rid of statistical anomalies there is basically no reason why your score should be awful. There is no way a school like Caltech will say 'oh wow 800 on the quantitative you are accepted'; their average acceptance is 790 in engineering, everyone has high scores. Conversely a sub 750 score will probably result in an instant visit to the trash bin. The GRE doesn't give any insight into the nature of the top applicants just serves as a handy first cut. On the other hand a great LOR from a legend in the field, or a list of first author journal pubs, or a perfect GPA from a top institution probably will get you acceptance. I think basically my point is that the GRE is irrelevant.... as long as you don't screw it up!