Japin is the person who runs DAT Achiever without a doubt.
Run a search on his past posting and you'll see exactly what I mean. Only posts when it has something to do about DAT Achiever. A person with a little common sense could see through the content of the posts made over the past 6 months that this is certainly the case.
Although one of my friends who took the exam LAST YEAR and used DAT achiever and said it was a valuable tool and saw a few questions appear [cool but isnt this illegal?]..... i ended up buying this as a bday gift for my cousin who actually recently used the achiever this year to prepare her for the test. She stated that it wasn't helpful for hte new style of DAT questions that everyone has been touting about. granted she did say it was good additional practice, she went as far as saying the achiever tests were a bad caliber of your performance on the actual dat test meaning that the achiever wasn't a good predictor of your final score and gave you false sense of INsecurity (although she did thank me for the gift). it seems like both topscore and dat achiever judging by a few posts are becoming outdated, but doesn't rule out that you should'nt use them.
but then again what do i know? In other words, take everything you hear on SDN with a little grain of salt, especially from me or japin. make your own decisions.