If it turns out that they will own a bunch of AA and higher credits of companies everyone has heard of, there may not be much utility. Very few companies have trouble with their debt, very few. The notion of avoiding single stock risk in this part of the market is not as great as other parts.
However, if these funds will have exposure to lower quality, as a segment of the market, there could be some utility. It seems like most high quality preferreds yield in the sixes. A fund that reaches for yield in lower quality issues could be worth a look at a time in the cycle when lower quality makes sense.
We'll have to stay tuned on these.