Another alternative mortgage lender is testing the waters with a 50-year loan product. But while Mortgage Investment Lending Associates, better known as MILA, prides itself on innovation, officials aren’t sure that there is much bang-for-the-buck in going beyond the half century mark. MILA rolled out its suite of 50-year products for its nonprime and Alt A loan programs in late June. On the subprime side, the 50-year option is offered on 2/6, 3/6, and…