Slurp, the cold tolerance of an F1 is near, or the same. as a pure northern. I personally can't see any possible advantage for any Florida genetics in northern waters, and can see a lot of downside by adding Florida genetics in Iowa. I would expect the F1 to grow poorly, and Fx to repress future growth potential over pure northern black bass, or at best, no gain or loss over pure northern black bass. The Florida side of the F1 needs a long, warm growing season that Iowa just can't provide.