Interest-only loans have rapidly grown in popularity over the last year, spreading from prime jumbo borrowers to the subprime market, but Wall Street analysts remain divided over the product’s potential risk to borrowers and investors. “In terms of the IOs, I find them a little scary because they can be much riskier, particularly for the subprime borrower,” said Susan Kulakowski, chief knowledge officer of MBS at Dominion Bond Rating Service. Recent Dominion research, based on…