thinking about doing Florida 70.3 HIM in May. How tough is this one?

I haven't done the Florida 70.3, so I can't say.  I've only done the SC HIM in Greenwood twice, and the Gulf Coast HIM last May (Panama City Beach). 

Gulf Coast Half: I would definitely do it again.  Beginner friendly, I thought.  VERY generous cutoff times.  The ONLY problem with this race was the inferno-like heat on the run, for which this race is famous.  I packed my tri top with ice, and was fine, but I'm slower than a turtle and don't much care about speed.  My vote:  Consider doing this race next May.

SC Half: I've done it twice.  Great course, well-run event, except the bike course is somewhat hilly and pretty challenging for a beginner cyclist (such as myself)

If this is your first 70.3 then it's perfect with the only downside is that it can be really HOT and humid on race day as was the case this last year.  The swim is in a calm lake where the water tempature is warm but you can't wear a wetsuit.  The bike and run course are flat and fast and the couple small hills you encounter are nothing.  Even though the tempatures were hot there was plenty of aid stations along the way stocked with fluids and ice.

My advice is leading up to the race practice open water swimming without a wetsuit and stick to a nutrition plan and don't try anything new on race day especially if there is heat.  I came off the bike and could of done under a 5:10 race with ease but I messed up my nutrition and ended up with GI issues on the run.