That makes sense to me. Thanks. I'll give that a try next time the sun is actually out. It's been overcast for the past 3 days with no end of the clouds in sight.
If I undertsand this concept correctly, it doesn't matter if the sun is out or not. You should be able to "set" your exposure in ANY lighting condition. So Grey Card and Check in overcast conditions should result in the same EC... IMHO.