By Katia PorzecanskiHedge fund managers often get a reputation for being greedy and unwilling to acquiesce to the changing demands of the money-management business. But in the face of investor backlash over middling returns, they’ve made a range of concessions to stay afloat.A Credit Suisse Group AG survey found that 76 percent of investors in hedge funds are benefiting from preferential terms or fees, compared with 9 percent in 2009. Over the last three years, use of the controversial 2-and-20 fee model has fallen 65 percent, the global survey found.