I hope nobody thinks that a digital body will give random exposure values just because it has a digital sensor.
The exposure reading of a digital camera is not exactly matching the exposure in the FILM-ISO standard - OK - but it is not without correlation to light
0.66 is not a small mistake and certainly it cannot be considered satisfactory for slide film use. But once one gathers - after a little experimentation - that his digital camera is yielding results which are let's say 0.66 EV "more" than what would be appropriate in the FILM-ISO standard, then one compensates and the reading is reasonably accurate along all its EV range.
The greatest source of exposure mismatch is probably the "matrix" or "pattern" camera metering as that will introduce some "guessing" by the camera regarding which part of the image is the one the photographer would - likely - consider the important one. So that is never comparable to an external light meter reading which averages the scene in front of him.