there have been various other devices produced locally
Sadly, that's the case, they are quite often incompatible with each other. Each has their proponents as the ideal system whereas they all have their drawbacks. Popular amongst the glider fraternity is Flarm, a clever system that, as I understand it, only alarms when there is a closing threat. I don't think it's had much takeup in powered aircraft. What we need is Government to take the bull by the horns and mandate one system for all airborne vehicles, over 250 grammes in mass. I don't expect the Gov't to do so, in my lifetime...
In Class 'G', Mk1 eyeball is your best system. In controlled airspace, a Mode 'S' transponder and a Radar service will be the best.
TOO