An annual benchmarking survey of nonprofit sector retirement plans shows broad improvement, but the survey's sponsor says financial advisors are needed to close the still yawning gap between 403(b) plans and their corporate cousins, 401(k)s.

Aaron Friedman, national nonprofit practice leader of the Principal Financial Group, which sponsored the Plan Sponsor Council of America survey released week, told AdvisorOne that in areas like investment options, investment policy statements and participant education, advisors have a role in "modernizing" 403(b) plans.

A good example would be in the area of default investment options, where the survey shows that 72.5 percent of 403(b) plan sponsors are now using target-date funds, up from 69.1 percent in 2010. But Friedman said 22 percent of plan sponsors are still using money-market funds as default options, a practice mostly abandoned by 401(k) plans.