So my question is this: If I leave my current dojo to go practice with someone else (maybe one of the runaway sempai) am I committing a huge breach of protocol? I feel like I would be insulting sensei to do this, but I also feel like I need to find someplace where I get positive energy when I'm on the mat. Any suggestions?
It is your choice. You decide. As it seems the senior students who left did not create a new dojo jointly but several small ones, I do not suppose your old dojo energy is anywhere to be found though.