While exchange-traded funds are soaring in popularity and investor cash continues to flow liberally into retirement accounts, closed-end funds have all but been forgotten by a large swath of the advisor community even though they offer some pretty compelling and unique benefits.

Unlike a mutual fund or an ETF, closed-end funds don't issue new shares as more investors jump on board so their share prices -- closed-end funds are listed and traded just like a stock -- reflect the true value, good or bad, of their portfolio holdings. Sometimes they're really pricey. Other times they're a bargain.

Either way, once you're in, you're 100% invested and don't have to worry about or account for the redemptions and withdrawals that happen regularly in mutual funds and ETFs. That's particularly appealing to retirees looking for a sustainable and predictable flow of income in retirement.

Also, these actively managed CEF's can issue preferred stock, auction rate securities and long-term debt to raise more capital to invest in the hopes of garnering larger returns for shareholders.

The problem, according to some 805 investment professionals polled by Harris Interactive on behalf of Aberdeen Asset Management during a one-week stretch in March, is that advisors only have access to limited amount of research and data on these closed-end funds.

The survey found that 67% of advisors who currently recommend closed-end funds to their clients want more information on these relatively obscure investment vehicles and 61% said that expanded research coverage of these funds would increase their likelihood of recommending them to investors.

And 44% of advisors who have already added closed-end funds to their clients' portfolios have done so even though they feel the information they receive about these funds is "inadequate."

"The most illuminating result of the closed-end fund survey is that more than 75% of financial advisors are hungry for additional research coverage and/or increased communications from sponsoring asset management firms and other parties," Gary Marshall, head of the Americas group at Aberdeen Asset Management, said in the report.

Of the advisors and firms who are recommending closed-end funds, 24% have more than $100 million in assets under management. More than half (53%) of the advisors who are not recommending closed-end funds at this time said they're avoiding them because there's a general lack of both research and institutional knowledge about these funds.

Sixty-two percent said third-party research ratings, when they can be found, occasionally influence their recommendations.

"Closed-end funds, one of the oldest types of investment vehicles, offer a unique set of opportunities for investors," Marshall added. "Their stable asset base and the ability to remain 100% invested—rather than account for daily redemptions and withdrawals—make closed-end funds particularly valuable for investors seeking recurring income and an actively-managed approach to global and emerging market investments."

There's no question, at least in the minds' of advisors, that closed-end funds can be extremely useful and profitable for all types of investors.

Ninety-nine percent of respondents who have put one or more closed-end fund into their clients' investment basket said they're suitable for a wide variety of client portfolios, including individual retirement accounts (89%), post-retiree income generating purposes (80%) and general savings or investment accounts (80%).