On advice from trusted codger I now only feed for winter stores 2 sugar to 1 water and heat mix to 180 degrees. Kills all and never molds. I haven't had any issues and only had my first loss this year. They died late winter, one out of five. I'm in SE PA.
Unless they are short, my girls ignore the sugar water in hive top feeders when nectar's available.
I'm not discounting the HMF. Bees go about their business with no concern for our goals and one keeper's sacred procedure is another's disaster. The small small starter books are great, but since location greatly affects success even within the same region, I enjoy my own mistakes and make up my own mind.