Yes they are reliable as we only specify verified and tested kit with the correct frequencies used. The only downside is you always have to have line of site from point to point (buildings and trees can be an issue) and sometimes, on rare occasions, if high sided vehicles pass or park in front of the devices the signal can drop. OLS install many of these systems and can confirm that in general they work very well if the design is correct which is something we always pride ourselves on.