first time i took the DAT i got a 16 in gchem, second time around i got a 22. i used kaplan to start with, because as you said it is a little less difficult, but the format is comparable to the real thing. Destroyer may be a little overkill, but I feel the finer details in that book definitely helped to put me over an 18 in gchem. its not as difficult as destroyer, but if you could do those questions you'll nail the test.