mudguard I use now for about 6 months and ~ 2000 km on my 29 "mountain bike. So far my back
remained always nice spared from splashing, so I am very satisfied.
Also, by design, it fits well with my Cube MTB. In addition, the Assembly & Adjustment is easy.
Safety:
A substantial disadvantage in comparison with tightly bolted mudguards is definitely the theft security.
So far, I was riding my bike several times at work and in the city center (city), making the bike
was several hours unattended. Fortunately my guards never got lost here ...
Let's hope it stays that way and that your get no "feet".