That is true about having a dyno. However it all boils down to monitoring knock and and a/f ratio, that is 80% of you tune right there. All the EMS’s out there are basically the same, and so are all the internal combustions engine (except the rotary) Knowing to pull timing and add fuel at peak torque for example is elementary knowledge regardles of what the EMS is.
Who do you think is a rputable tuner? I am not saying there isn’t one, but I am asking.