My opinion is that the revised GRE test will be significantly less g-loaded than the current test. The most significant change is the removal of analogies and antonyms, which are standard items on IQ tests because of their high g-loading. Performance on difficult analogies and antonyms is often what separates the elite scores from the good scores. The changes will make the GRE less of an IQ test for native speakers and thus easier to crack through study and memorization. It should be easier for both native and non-native speakers to get high verbal scores on the new test.
With the above in mind, if you are able to score high on the current Verbal test, my thinking is that you should take the test before before the changes go into effect.