Dslrs gear doesn't mean that somebody with talent, creativity etc...can't do great stuff with those and win an oscar.
But we should be clearly aware of what does it means in terms of hassles, false economies, and limitations and their impact compared to dedicated motion cameras into the business models of each pro.
My suggestion to anyone making the addition of motion imagery to their still repertoire is use what works for your business, not the art.
The art is easy. I mean if your going to build a reel, or test, or shoot some psa's, editorial whatever to get your feet wet, nobody will care if it's shot with a RED, an Arri or a 5d2, unless you have some major issue like moire or bad color grading.
The business side is more complicated. Some client's expect a better camera than a dslr on set, some don't care, but I wouldn't suggest overspending, at least not in today's world.
Having video experience has been good for our business, but it's a double edged sword, takes investment and risk and a huge volume of time.
You also have to be aware that the world of motion imagery has been tightly squeezed. What use to be a low budget movie at 2 million is now half a million to 800 thousand, sometimes 1/10th of that.
So those directors have moved more into commercials, even very accomplished directors with huge CVs. In turn that moves the medium range of directors more towards web and display video, which puts more pressure on photographers trying to get a handle on how to profit from motion imagery.
The one thing still photographers offer that the motion guys usually don't is the ability to work with smaller crews, usually with faster on set turnaround. It's not unique for a still photographer to be part director, dp, camera operator and even part producer, where in the film world, it's rare you'll see a director holding a camera for any period of time.
Regardless, IMO, the best camera for building your reel is a 5d2. It's fast, it's easy, goes to mega iso, and except for the sound issues and sometimes moire it's a very workable camera and file and lenses are everywhere.
For heavy lifting the air becomes more rarified.
Personally, I've used about everything but the Arri. Nikons, Canons of all kind, the sony fs100, even the little Panasonic. I still think the 5d2 is probably the best due to it's weight, iso and availability and though you need some time of sound recorder, once again it all depends on what you shoot.
For real world work, I love the RED One's, today even better than our Scarlet, because even though the R1 is heavier it's a lot more simple camera to work than a Scarlet. I assume the Epic is about the same though haven't used one.
Once I use the Scarlet more I might change my mind, but (knock on wood) our RED One's have been very dependable.
In summary, digital motion really does mirror digital still photography. You can build your body of work with smaller, easier to use cameras and when the time comes, step up to something more expensive in either purchase or rentals. Just don't overspend, not if your in business.