They lose the OVF for video but they have probably never operated a motion picture camera that wasn't EVF based - i.e. some form of video camera.
Yet to do a shoot on a DSMC Epic or Scarlet, or REDONE, particularly when extracting stills from the movie, you lose all of that: no OVF, lower MP, compressed files; requires high powered (daylight preferred) continuous lighting; etc.
Doing a studio magazine shoot or something similar with a REDONE/Epic is a very cool concept that has its place, but I think in the long run it will be the exception rather than the norm if the main interest is stills. There still is too much size difference - and more importantly the huge difference in the lenses, lighting, setup, and other production accoutrements that go along with a motion shoot - to make it a total game changer.
I think it is much more likely that 95% of epic owners (and even non-owner users like David Mullen) will have an $1800 Canon 7D or equivalent in their toolkit than that even 50% of pro still shooters will have a full fledged DSMC like a $3000 to $50000 Epic/Scarlet.
Again, nothing wrong with that - "horses for courses". I like the fact that Epic/Scarlet CAN do it all, but it doesn't mean it will be the BEST tool for the job.