Yea, DP8 is great for playing back video. If you are scoring a film it has it all over Sonar with it's "chunks" and Streamers and other features .
The notation in DP8 is way better, but still not anything to get excited about. Still clunky way to work. Lead sheets out of Dp8 are waay ahead.
Sonar's Prochannel and other mixing features are by far better than DP8. As is midi editing.
DP8 does not handle 64 bit plugins very well. If you are going to load up an Orchestra you will most likely need VEP 5 or another 3rd party app outside of DP8 unlike Sonar.
You can change colors in DP8, but Sonar is still easier to customize. Sonar is easier with Screen setups and Screen Shots..
I can see me using DP8 for film work, but Sonar will be what I use to create and mix a song.