It would be nice increase the macro options available from 3 to 4. On my delta I like to do a quick check the bed height on 3 points aligned with the towers and a 4th in the center .
(see calibration G-Code). The File i use is called towers.gcode which runs the extruders to each of the towers. If you want to have it pause at each of hte towers, I believe if you add an M0 into the g-code and print it using USB (not sd card) s3d will pause at each tower.