I've been trying to substitute whey for buttermilk in other pancake recipes and always got this sweet / sour taste, good but you could tell something was very different. (kingarthurflour.com)
I think the 15 minute wait is key because I have made other pancake recipes that were flat, and I know they didn't call for resting the batter. (kingarthurflour.com)
I used whole wheat pastry flour which has worked fine in other pancake recipes and banana bread. (simple-veganista.com)