There are some counter currents that form as a result of gulf stream eddies. In a south
wind these N>S currents can produce some chop that counters whatever benefit you get from extra 1/2 or 1
knot you get from the eddie.
If you can make 6 knots you can time most of the bridges well and while there are a lot of them, you can easily make
Miami in an easy two days... one day if you really push it. If your speed is closer to 5 knots you may not be able to time the bridges quite right and waste a lot of time spinning in circles.