I think what you are looking at is ground-based TIS such as they have in the USA, where the ground radar sends its traffic picture to all suitably equipped aircraft, in a brief squirt of data within the normal Mode S interrogation.
It's possible that ADS-B equipment would display traffic on the same screen in the GNS430 or whatever but I have no idea.
If you look at how many people moan about a £5 increase in some landing fee, and look at the ongoing war over Mode S, and the general resistance to carrying or using Mode C (thus making an RIS worth very little much of the time) I wouldn't lose any sleep over whether your existing avionics are ADS-B compatible
