I live in COOOOLD MN and we use the Moho all winter long. I blow our lines out every fall (just did this about 2 weeks ago) and pour the pink down each drain. This has worked for me for many years. I used to run the pink through the lines, but I do not have a water heater bypass, so I could never get it into the hot water lines anyway.
If I had a hot water bypass (old water heater that the kits do not work on) I would blow and run the pink... I could do this in about 20 minutes total, so once you get used to doing both, you'll be good to go.
I leave my pump on when I first start to blow the lines. This removes the water from the from the pump, as far as I can tell.
I would never leave water in the lines in the cold. As the very least blow them out with 50 psi and blow until you see no water coming out. I do pause the air and then repeat and the first few times after I pause, I get a big flow of water, so pausing and repeating is important.
Good luck!!!