Hi
I took both the DAT and the MCAT. I decided to switch to dentistry. Anyway, I did fine in both of them. I don't know whether I should say that the mcat is much harder, but it's DIFFERENT. In the mcat I found myself thinking much more while in the DAT it came down to the fact whether I know the answer or not w/o much thinking (except a few questions). I found myself memorizing stuff for the DAT and learning all the plants/taxonomy stuff which wasn't on the mcat. When I was studying for the MCAT I tried different approaches on how to attack the passage and get most of the info out of the passage rather than memorizing as much as possible. Also, the DAT had math ( which sucked). HOwever, the DAT doesn't have physics which makes it easier for some people.
hope that helps.