They are semi-technical, in my opinion. I'm not sure what classes you have taken or any of that, but these aren't like real scientific research articles. These are more of.... I don't want to say dumbed down.... but more like an overview of research. They never get terribly specific with information, and they aren't that hard to comprehend. I always thought they make it difficult by wording the questions in a weird way, or having debatable answers. I had one asking me if the a statement was true or false, but the question boiled down to how literally you interpreted the meaning of one word in the question. The weirdest passage on mine had questions involving concepts that were introduced in the paper, and expected you to apply them to general situations.
And I don't really understand why people keep claiming Search and Destroy doesn't work in such a broad sense. I'd say for mine, which I took a month ago, I could still safely use it for over half of my RC. There were about 5 questions that I wasn't sure about when I finished (I apparently missed them all, ha). I'm sure it's different test to test, but even the tone/inference questions don't honestly require you to read the whole thing. You can usually pick them up from reading the paragraph of interest.
If you want to read something extremely dense, and then feel a bit better when you see these passages, go to the journal of cell biology, or pubmed and read some of those articles and try to understand what is happening. It will be overwhelming, and you may have to take it a few sentences at a time, but it is very good to MAKE you break down what is being written. It's very easy to have a tendency to just skim papers and whatnot just because you never have to analyze anything in day to day reading. I had to do that for a few undergrad classes this past year, and while it was very frustrating and boring at the time, I felt like it was good for me. This may or may not help, but either way, you'll feel better when you go back to DAT passages, haha.
Oh, and in regards to it being similar to topscore: I felt like the passages themselves were extremely similar, but the questions were a bit more difficult. Topscore didn't use any tone/inference questions, but the DAT most certainly does. As far as difficulty of reading and whatnot though, I'd say Topscore was accurate. Just expect one article that isn't science related.