I’ve used them off road generally trouble free though they do seem susceptible to bits of grit getting under the seals and causing creaks.
Any known problems?
I’m thinking of replacing my bent Campag UT crank with an FSA slk or similar and then fitting a stages power meter to it when the mega exo version is available (no stages system available for UT) so they seem to kill two birds with one stone and come up pretty cheap s/h.