Hi MidEastGal - sadly, not a lot of people have experience shooting video with both DSLRs and DSLMs, so you will hear a lot of opinions that are somewhat less than well-informed. I have shot video and stills with both types of camera, and once people go high-end mirrorless, it is very rare for them to go back.
Here is a little video-centric matrix that may be helpful:
Canon DSLR: Clip limit - 12 to 30 minutes; Video autofocus - no (except T4i); Video viewfinder - no; Silent autofocus lenses - no
Sony DSLT ("T" is for Translucent Mirror): Clip limit - 30 min; Video autofocus - yes; Video viewfinder - yes; Silent autofocus lenses - no
Panasonic DSLM: Clip limit - hours; Video autofocus - yes; Video viewfinder - yes; Silent autofocus lenses - yes
DSLMs are
not perfect cameras. Although my GH2 takes fabulous stills, my old T2i was a better still camera, in my view. But, as cameras designed from the ground up for video, they are a much better blend of still and video capability than legacy DSLRs. And they are lighter in weight, smaller in size, and often less expensive.
Here is what Will Crockett at discovermirrorless.com says of the new GH3:
Again, hope that is helpful!
Bill
P.S. - it's not me calling them DSLMs, it's
Panasonic
P.P.S. - I didn't invent
DSLT either