Is there a reason to Use dried blueberries rather than fresh or frozen?
Fresh/frozen will have a higher moisture content and would probably have less of that "dried" flavor. I think dried tastes different, maybe some people can't tell the difference.
I've heard that dried fruits can have a higher chance of molding too. Dried fruit may be less dense than your KT, which would make them float, and exposure to air could grow molds.
Fresh fruit would have a higher density and should sink, but frozen would probably float since crystallized water is less dense than liquid water.
Of course this all depends on total water content and the density of the mass you are adding.
Fresh fruits would always be the best choice. They'll even have their own microbes on the surface to aid in fermentation. Anything not compatible with KT won't last very long in the acidic solution.
Frozen fruits would be your next best. You will lose some microbes, minerals and enzymes to the freezing process.
Dried fruits I'd choose last. Not that they are bad, but if there are better choices, it would make more sense to use those instead. But if you live in a place that can't get fresh/frozen mangos, you want mangos, and your only option is dried mangos; then the best option is the only one you have.