I went to Miami, FL in Nov 05 and took my Ikelite housing as a carry on. But as someone mentioned already, plan to get early to wherever you go because most screeners don't know what a housing is, then they take it to another machine where they check for explosive powder or something because they brush the equipment with a cloth and put the cloth into a machine and finally after 5 min or so, they give our equipment back and then you have to take the time to arrange evrything back in order in your carry on. This happened every time i checked in to an airport (Phoenix and Miami).
Just be prepared. I would not take the chance of having my housing checked in because airlines lose baggages all the time, even though you have insurance, you will ruin that particular trip if they lose your housing.