Taking everything into account we finally went for the easier 30 year mortgage plan when we bought our first tax lien certificate. Although a number of things had to be pondered over, eventually the choice was made for us. The main reason was that I found out my wife was pregnant. Her regular monthly income would become unreliable because she wanted to be at home raising our child. Our monthly payment would have been too high if we had committed ourselves to the 15 year fixed mortgage plan. We could see the financial problem of getting in too deep even though there were benefits to a shorter loan period. A thirty year loan brought the monthly payments down to a reasonable level.
During the year we can make additional payments which helps to reduce the amount owed and increase the ROI on the tax lien certificate investment. To our surprise we also discovered that we could knock years off our loan by doing this. Although this isn't easy to achieve, in the long term it is well worth it. It was hard going against our preference for a shorter term, 15 year fixed rate mortgage, but we had to think about more immediate needs and abilities. In retrospect, everything worked out ok for us by going down this road.