The advantage of cutting into slices before cooking is that you can brine them thoroughly with Kosher salt. It really brings out the juices and adds to the flavor. Fortunately using Kosher salt for brining keeps the saltiness level just right when you eat it the following day. As far as temperature, I would normally do it at about 130 degrees for myself but several of my guests have a weird hangup over seeing too much red in meat so instead of cooking it medium rare as I would do for myself, I allowed it to heat to result in medium well done. My slices still had pink in them and were juicy.