Fixed-rate mortgages with 15-year terms are good products for low- and middle-income borrowers or have limited appeal for such borrowers as well as for lenders, according to competing think tanks.Co-directors of the American Enterprise Institute’s International Center on Housing Risk developed the Wealth Building Home Loan that Bank of America started offering in September. Edward Pinto, one of the co-directors of the AEI’s center, said the 15-year fixed-rate WBHL requires little or no downpayment, due in part to BofA’s partnership with the Neighborhood Assistance Corp. BofA will also provide a subsidy to decrease the interest rate on the loans. Pinto said the loan has much less foreclosure risk than a 30-year fixed-rate FHA mortgage due to the equity building ...