I haven't heard of any, but there is often a "boat bash" concert or something going on. We didn't get one last year, but there was a gig in Miami for the people who went down that way, I believe it was made up of local bands. In 2015, the pre-cruise concert was in Ft. Lauderdale and had some good bands, again mostly from Florida, though Thrash or Die for example is known outside of Florida, too. I hope we can have another show like this, but who knows if it will happen. It's a good place to drink beer and meet other cruisers.
Maybe someone who knows the metal scene in Miami better than I do will chime in with some good local show happening on one of those nights. I'm definitely down for some dive bar metal music and drinking.