Used canola oil instead of "liquid shortening", upped milk to 2c, reduced sugar a little.
Came out really good, fluffy and moist on the inside. Expected vinegar flavor not detectable. Not anywhere close to the holy grail of the dense, bready texture possessed by Dutch Eating Place pancakes, but a fine meal anyhow. (Maybe the extra milk is partly to blame though?) I was vaguely hoping the vinegar-baking soda reaction might be key to "Amish style" pancakes since I'd earlier found it on an Amish recipe site.