Originally posted by falconeye Only because -- of course -- slrs, by definition, have no EVF. You argue by using a logic tautology.
Depends upon the kind of shooting. While on sticks or in stages situations with a dedicated focus puller, external LCD with features like focus peeking, zebras, etc is very useful. When on the move - run 'n gun - with the camera on a shoulder rig or some other type of support, EVF (for those cameras that have them, i.e., Panasonic GH2) can be useful.
dSLR users often use rear LCD loupes like this one:
You've got to remember that video is often locked down to 1/50 or 1/120 shutter speed, so camera support is critical. Some type of EVF creates another contact point, which helps greatly.
EVF or no, I'd be surprised if Pentax can attract people already shooting video with their Canons and Panasonics. That ship has already sailed for many folks...