We are new to Fl. We just moved to Windermere and the kids are at both elementary and middle school level. My older kids are in the advanced math and don't feel the work is any easier than in Pa(where we came from). They have already learned some of the material they are doing now though. My elementary kids on the other hand are doing much more advanced work here than they did in Pa. It doesn't seem to be harder or easier, pretty much right on track.
My husband and I heard all the same things as you, and I know there are some counties and schools that are not great, but I think what happens is that people get stuck in how things "used to be" and even when things change for the better, there is still a stigma. We chose our schools first and then looked for housing in the areas of those schools. It seemed to work for us and I am not concerned about my kids "getting dumb" as a lot of people from home had told us..lol. Good luck!!