Well, I can tell why i would like some signal out from the camera.
I do not want to use the usb because of complexity, but a pc sync cable (used to trigger remote flash on cord.)
and with the magic lantern, i can use a timelapsefunction, which can calculate so the movie would be nice and smooth exposures when taking pictures of a sunset.
these do increase the shuttertime after a while.
and therefor i would like to have a signal from the camera when telling its don taking pictures, or the whole time its taking a pict. 