I'll testify as well that a real siltout is a different experience from being in the dark. I had the pleasure (and it was) of getting to experience this under the supervision of an instructor/friend, who had offered the experience as an option for me and my husband. Both of us were fully trained cave divers before we did this, though.
I saw the "siltout" portion of the original post, and seriously wondered if this instructor intended to silt out a wreck with recreationally trained divers in it -- I hope, at the very least, that they had some training in line following and that there WAS a line to follow, and that the space they were in was not extensive. So many things can go wrong in such a setting . . . there is a reason why instructors for overhead environments are required to have such extensive training.