k-1 electronic shutter is only used when pixel shifting, per the camera specs on the pentax site, although someone in a thread out here did mention a menu item for electronic shutter.
afaik, efcs can only be used on a dslr in live view/mirror up modes, and a dslr using live view has the same shutter functionality as a milc does, so it'll have the same shutter shock issues, see the shutter shock problem on the d810:
Nikon D810 First Impressions Review: Digital Photography Review
don't use live view/mup on the k-1? you'll have to deal with mirror vibration, this is what it looks like on a d800, blow the pic up to 100%:
http://horshack.smugmug.com/photos/i-Bb5WTmF/0/O/i-Bb5WTmF-O.jpg
---------- Post added 02-27-16 at 02:00 PM ----------
Originally posted by 2351HD Nikon did that with the D810 I think.
the d810 got a re-designed shutter, over the d800, but as you can see, it still has a shutter shock problem.