Arguably, if you use the I.R.E. 1 index for shadow readings, your need for the Zone System will be reduced. If you decide to use the Zone System as well, the I.R.E. 1 to 10 scales will tell you almost all you need to know about exposure; very roughly, if it's well within the range, use N+ development, if it's much outside, try N-.
It's a very good meter. My wife uses hers all the time. For very low light (i.e. shadow readings in poor light), however, ANY spot-meter is pushed hard, even the legendary SEI.
Cheers,
R.