I have two friends who have had total failures of Romeo Zeros in EDC roles- both of them had a maximum of 50 rounds on them. One simply died and wouldn’t turn back on despite known good battery changes. The other had a failure of the frame holding the emitter in the body after a (literal) 1.5 foot drop onto concrete in a garage. Went from a dot to a diagonal streak across the entire screen.
In both cases the units were promptly replaced by SIG, and despite my best efforts my friends won’t go for something more robust, but neither of them is what anyone would call a serious shooter.
I think it would be difficult to epoxy-pot the interior without locking up the adjustment mechanism.