While I agree that home grown fruit tromps store bought fruit any day, growing citrus in South Florida can require more attention. Yes, there is the "threat" of greening (which I havent seen a lot of in this area, there is also canker, leaf miner, mites, soil condition issues (ground holding water, composition of soil, etc.) and other problems that can affect citrus here.
I don't want to say you cant grow quality citrus here, I do want to alert/advise that it can be fruit that requires extensive care/hihj maintenance at times to be successful.
If you want a citrus (grapefruit, lemon, lime, orange, tangerine, etc.), than plant a citrus of your choice. If you want a fruit tree that provides shade, there are many other options that may suit your shade needs that will be a more reliable producer with less care.