Haven't posted for a while, but the problem with sirloin is that at the lesser grades (I am sure they are not using choice) that the cruise line is buying will be very unforgiving. Cooking a lower grade leaner cut for the mass of people they have to serve is going to be very hit and miss (probably more miss). Better to do a thinner or smaller rib eye which will hold up much better sitting under a heat lamp due to the higher fat content of the meat.