I am suspicious of these things. I poked around in the web site you posted. The "stable value" is thanks to an "insurance wrapper". This means that some of the yield is given up to the entity that provides the guarantee.
Sounds to me like something cooked up for brokers to sell to bubble busted investors. These funds look to be short to intermediate bond funds with some extra fees for a stable value "guarantee" plus some more extra fees for the soothing sales pitch. Nothing will go wrong because our clever financial engineers have bought some derivatives and besides Joe's offshore insurance will bail us out if things go wrong.
shows their graph of the contents of the average stable value fund. What catches my eye here is that half the portfolio is in "Synthetics" aka derivatives. Derivatives have their uses but a lot of toxic waste is created by the financial engineering process and it has to be parked somewhere. Where better to park the unsalable tranches than in a product marketed to risk adverse individuals. Think of a sausage made in southern China, guaranteed to be safe by the manufacturer.
If Vanguard were to offer one I might look closer at it. Otherwise my take is that these are going to be high fee, lower performing (because of the fees) vehicles. There is a reduced risk of moderate loss but at the risk of catastrophic loss if the sponsors aren't as clever as they think they are.
The value of any fixed rate instrument varies as interest rates change. You can pretend it isn't happening by buying CD's or individual bonds and holding to them maturity. But the bottom line is that when interest rates go back up, those holding low interest rate paper will be hurt.