"DE students are more likely than AP students to go to college, but are less likely to enroll in a four-year college." Determinants of Students’ Success The Role of Advanced Placement and Dual Enrollment Programs by Cecilia Speroni.
Pretty much all you need to know. If you are just trying to hit a metric that says more kids will go to college then you can focus on dual enrollment. But if you want to ensure students are having a quality pre-college experience that leads to a four year degree, you better get them into AP.
For more - http://www.aypf.org/forumbriefs/2012/fb021012.htm