For what it’s worth, I’ve had the rear seatpost mounted one and other than having to do it up really tight to stop it spinning it’s been about what I expected- not as good as a proper guard but significantly better than nothing. I prefer a proper guard, but the mn one fits a lot better with the reverb. Not long enough to be useful on a 29 though.
I was fairly impressed it survived acting as the intermediary in an arse/tyre interface completely unscathed though. I did have a couple of thoughts about improving the clamp area, whether they ever get done is a different question.