You don’t have to beat yourself up over making more money on the service and maintenance (S&M) side of the business. This slice of the total pie is growing. “It makes up roughly 40 percent of our total revenue,” says Darryl Keeler of Tech Systems, the Duluth, Ga., enterprise electronic security systems integrator. Some other firms say they pull in 70 to 80 percent of revenue from S&M.