I think having words occupying single cells is ok, which is roughly what we have here, and I've seen the device quite often (Schadenfreude liked to do it, usually with clashing entries). So I think it's ok, even though it's not flagged as such in the preamble, and uses a 'disappearing' act instead (which might be a little unfair, I suppose).
I found the clues difficult but got lucky with 15ac+17d very early on, so got off to a good start.
I'm a bit biased, though (I've enjoyed nearly all of Vismut's puzzles so far).