Because the bootcamp industry hasn't been around very long, you're right, there is no good data. But from my experience and the experience of my peers in my class, I believe that adapting to new technologies/new ideas is actually one of our main strengths. Those skills are essentially a pre-requisite to getting through the program.

Your question about the potential to have a normal software engineering career trajectory is a good one (one that I am particularly interested to hear the answer to) and that's why I wish that more employers would speak to this issue. I would venture to guess that my employer would speak highly of Hack Reactor and how prepared HR grads are because they have continued to hire from there, but it would be nice to see how employers actually review these schools and not just the students.