I faced this exact choice about 3 weeks ago and decided to go with the PDX10. I do some light documentary stuff and wedding videography.

PDX10 Advantages
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Better audio
True 16:9 widescreen
more compact (especially when you don't use the
shotgun mic or large lens hood)

DVC30 Advantages
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Built in ND filter
Much better in low light (2-2.5 stops)
Better manual control

So it really depends on what you want to use it for. Like you, I think 16:9 widescreen mode will become more and more important, so I opted for the PDX10. My other camera is the Canon GL2, which is similar in capabilities to the DVC30, so I feel like I've got low light covered when I really need it.

Good luck with you decision!

-Jeff Smith