there are a lot of variables. If you are looking for a max HP tune then the Dyno is of course the only way you would ever know what you have. If you just want to be sure you are getting the proper mixture under actual driving conditions then a street tune might be better. I tuned mine on a Dyno then tweeked it on the street for low speed and highway cruise sections of the map.
I have no knowledge of the AEM EMS. I used an Ostrich Emulator with Tuner Pro and an Innovate Wideband O2 sensor.