One of Miami-Dade's top financial minds is warning that the Boston healthcare company that has expressed interest in buying Jackson Health System may be offering to take over the public hospitals without paying the county anything. In its letters to Miami-Dade leaders, Steward Health Care Systems of Boston has said the deal would yield an investment by the company of "over $1 billion directly to the communities of Miami-Dade County." But Leo Guzman, head of Coral Gables-based Guzman & Co., points out that "nowhere in the 'proposal' does it spell out that Steward intends to pay for these assets." Guzman & Co. specializes in institutional brokerage and investment banking and is a member of the New York Stock Exchange. Steward spokesman Bruce Rubin characterized the talks differently: "Steward's letter of interest proposed, subject to due diligence, putting a total of $1.1 billion into the hospital, which is losing hundreds of millions of dollars every year and is a growing burden on the residents and taxpayers of Miami-Dade County." Specifically, Steward's letters says it might "absorb" Jackson's debt — about $500 million — and invest $600 million in capital improvements.