Also there is bit rate for the footage. Sounds like these DSLR do around 45-50 mbits/s. HDV and most consumer HD vid cams are what, 25 mbits/s or less?
Bit rates in a tapeless environment are pretty worthless to determine video quality. The Canon DSLRs have huge bitrates but that's just because their codecs are extremely inefficient. That doesn't mean they don't take good video, because they do....but they shoot in a format and with a codec that just doesn't have as big of a bang for your buck as other codecs. The thing with Canon's is they also have clip limits and whatnot as well, which does hinder video shooting. But using bitrates to judge video quality on cameras today is just like using processor speed to judge the speed of computers, it's not all that is there which influences the end result.
However, HD-DSLRs are the future of filmmaking on a small to medium sized budget. Most 'pro' cams have 35mm equivilants around 28mm at the max (with a wide angle adapter you can probably get 20-24 without much distortion). However, you can get down to 14mm at f/2.8 on an HD-DSLR. If you have the right glass, shooting video on a HD-DSLR vs. anything sub $5,000 on the camcorder market isn't even a contest. You have to be creative with audio, but shooting audio separately or using adapters solves that problem.
I'm shooting a film in on a Panasonic GH1 this spring and it's without a doubt the best camera I've used in the sub $5k market outside of a 5D Mark II, but I wanted to shoot in 60p, so the GH1 was the best option. Being able to shoot video from ultra wide angles as well as being able to use an extremely fast f/1.7 lens for what amounts to the same focal length wide angle as a standard consumer cam will mean getting more shots and having more flexibility than any dedicated video camera can offer at a reasonable cost.
To those saying HD-DSLRs are a fad or a gimmick, I remember when people were talking about social media in the same way. Sure, HD-DSLRs aren't going to change how humans fundamentally communicate, but they are changing how digital content makers approach their content in a lot of ways due to the low cost of entry and the stunning results they can deliver in capable hands.