As forummm said, the argument should simply be the Total Returns. A good comparison to AZNCX is VWIAX, which is Vanguard's Wellesley fund. The funds are very similar. Both funds are also weighted similarly in large funds and focus on providing dividends. Both funds hold about 33% stocks. VWIAX holds 60% bonds, where AZNCX holds 30% bonds and 30% other (I didn't investigate what "other" was, maybe real estate?). Of course, VWIAX has a 0.16% expense ratio. It also has a $10,000 minimum (If that's a problem, you can still use VWINX which is the same fund with a 0.23% ER and $3,000 minimum).
To compare them, you can go to the
interactive chart for AZNCX on Morningstar and compare it to VWIAX: you can see that $10,000 would be worth $18,200 if invested in VWIAX and $15,600 in AZNCX (including dividends) after 9 years (that's how long AZNCX has existed). So they are sacrificing $3,000 over the last 9 years for the convenience of getting their money distributed back to them monthly. The chart on Morningstar includes all the dividends that have been paid out, so it's not added to the total return or anything. They are literally giving up profit in order to get bigger monthly checks.
If you look at the dividend and capital gain distributions, AZNCX does provide about twice the dividends as VWIAX. VWIAX pays quarterly and roughly 50% of the distributions are Long Term capital gains distributed at the end of the year. So if this is invested in a taxable account, they'd likely be paying less taxes on VWIAX distributions as well. But the distributions are less often, with a large portion of the distribuion coming at the end of the year. If they wanted bigger distributions, they could sell a small portion of their holdings periodically to get the additional cash they want and be much better off in the long run.
Of course, you can also point out that VWIAX charges about 10% of what AZNCX does for a very similar service. And I didn't research it really hard, there may be other funds out there that offer distributions that are more similar to AZNCX.