My husband uses a transmitter for his Vytec, but he is not and willingly says he is not DIR, although he took Fundies and has gotten UTD training with AG. His transmitter points down, so it doesn't get in the way of anything and it's not going to hit the ceiling. However, he has annoying frequent problems getting it to sync, and a valve drill kills that function. I, personally, have seen nothing watching him that has made me want to have a transmitter, even assuming the gauge I use permitted one.
There are a lot of people who are GUE or UTD trained, who elect after their training to deviate from the gear configuration and/or the procedures. That's certainly their decision, but those deviations are not DIR simply because someone with the training decides to use them.