I wouldn't worry about any tilapia surviving at our latitude as I've lost all of mine, whether "mixed" or blues, by the end of November. I'd check your local regs, however, as fact and logic aren't always the main consideration when it comes to regulation, especially of wildlife.
Stocked at fairly high densities, and especially if not fed, both species have been very helpful in controlling FA, IMHO, but a really complete control also will likely involve aeration, especially in really nutient rich environment.
One other word of advice: When you buy tilapia, whatever the species, specify that you want fish in the 1/2-3/4 lb range. Most sources sell by the pound, and you're much better off with a bunch of midsized fish rather than a lesser number of very large ones, for both breeding and algae eating purposes.
