Employees generally value their benefits packages, with a high percentage of workers reporting that their bennies are just as important to them as the salary they draw. But when the focus is on health benefits alone, workers, put off by higher out-of-pocket expenses, aren't sure how valuable their coverage is.

That's what Mercer gleaned from an ambitious survey of 1,506 retirement plan participants. Mercer does an annual workplace survey, and so has nearly a decade of data to draw conclusions from. Its questions on employee satisfaction with benefits revealed the harsh truth about employer-sponsored health coverage.

"Benefits remain a critical element of the employee experience, and the vast majority of workers agree that benefits are just as important to them as their salaries," Mercer intoned in a news release. "But … the perceived value of benefits is eroding among workers who complain about out-of-pocket health care expenses."