This scenario might work in some cases, but I don't think it would have for us. We made the 20% down payments on both of our mortgages. Our first mortgage (2010) was at a variable rate of prime minus 0.75%. We had to move in 2016, and bought the second house before the first one sold, so we had to take out a second mortgage. They had decent discounts on fixed rates at the time, so we took one at 2.39% (4 year term), which was not much worse than the variable rate would have been at the time. I shopped around, and there was no way we were going to get anything better in either case if we had only made a 19% down payment and paid the insurance. Both the mortgages were with the same big bank.