I personally have used Crack DAT Reading to prepare for the RC section and I found it to be very useful and quite representative of the RC section on the DAT. The lengths of the passages are roughly the same, as well as difficulty level and types of questions asked. CDR helped me build my reading speed/strategy and got me used to reading long passages under pressure. The only thing I would say is that CDR doesn't have many technical science passages, which is what the real RC section has. I combined CDR with TopScore (TopScore's RC passages are more technical and scientific). So the combo of CDR and TopScore helped me out tremendously to prepare for the RC section.