To visit the low-rise medical offices dotting the sun-bleached highways of Broward County is to meet doctors and patients who complain of being guinea pigs in a social experiment gone wrong. They are part of a five-year pilot program designed to test whether Florida can reduce spending on Medicaid, the public insurance program for the poor and disabled, by largely turning the program over to for-profit HMOs. Success would mean getting a handle on one of the fastest-growing and most vexing expenditures confronting states. But it's unclear whether the pilot, which is also underway in four other counties, has achieved that. Health professionals here say any savings have come at a high cost: the quality of care. And they are outraged over the legislature's decision last week to essentially expand the pilot statewide, which will be carefully watched by other financially strapped states across the nation.