I have been blowing my lines out for close to 15 years and have had one small problem when I must have forgotten to open the low point drain. Other than that, no problems and it's quick and, as long as you bypass the water heater after draining it, all you then need to do is put the pink stuff in the P traps and you're good to go. Just remember to turn on "all" the possible faucets and open the lines to the toilet. You probably have an outdoor shower, don't forget that and, if you have an outdoor kitchen of some sort, don't forget that. Also, blow out the black tank flush to make sure that one doesn't get frozen and cracked. The reason I like to blow mine out and not fill the lines with pink stuff is having to get it out in the spring when we get ready to go camping.