I had been working with an XL2 for a couple months and just got to use a DVX for the first time this weekend, and I gotta say I enjoyed using the DVX much more and I think it turned out better as well.
If you put the two side by side on the same scene, they would have different looks. Depends on which look your prefer.
The DVX might be slightly better in run and gun because you don't have to manually control the lens, but at the same time the XL2 has a form factor that some prefer for run and gun.