again, ocean water temp is different than closed-system water temp. think dilution of bacteria species.
this time of year, as temps rise, we see an HUGE influx of temp-induced vibriosis and other bacterial infections in the ER on a popular SH forum. the causes are pretty well understood, and it has been proven over time as well as with studies.
it's totally up to you how you run your setup, but if you're going to run it close to 80, do yourself a favor and stock up your SH med kit now instead of waiting for SH to present symptoms. that way you can jump on it right away. also, if your SH DO present bacterial symptoms, you'll want to drop the temp to 68* max to slow the progress of the infection.
to be honest, my electric bill would be much better off if i did away with the chillers on my SH setups, but i've lost SH due to temp-related bacterial infections, so i run them, and haven't lost a SH due to temperature issues since.
HTH