The Canon 7D, 60D and 550D (among other brands) can all shoot 720p @50p & 60p. Using this setting pretty much gets rid of any noticeable skew with fast action. Also, you can do nicer slow-mo shooting at 50 or 60p.Can you link me to any videos showing some fast moving action shot on VDSLR? I'm finding lots of videos with nice shallow DOF but those kinds of shots get old pretty quick in an action sports DVD and I also notice the shots going in and out of focus very easy.
Yes, you do generally get shallower DOF with the larger sensor but if you know about shutter speeds, Aperture, ISO and focal lengths you can get around it pretty easily (don't forget you have a focus ring to manually focus too!). If you are serious about your film making then get a VDSLR, it's a bit of a no brainer at the moment. If you just want to muck about and shoot your mates riding then a DSLR is a bit of a handful.
The Panasonic GH1 or now GH2 are also a good option. They have a micro 4/3 sensor which is smaller than the APSC found in the Canons. This means you get a slightly larger DOF for any given f-stop and they also don't suffer from motion skew (jello effect) as bad when shooting 1080p.
VDSLR's are all a bit of a compromise. I use a 7D for all my own professional work and definately wouldn't go back to a 'regular' video camera until they have sensors like we have in DSLR's (which isn't far away).