I have the newer version RNS-E and it isn't night and day better than the older unit but it is a little faster and you can use the larger SD cars plus traffic. With that I have the OEM Bluetooth wired in and people say the phone calls sound good. It is not the most modern, I haven't wired in streaming and you can't Bluetooth streaming with the factory Bluetooth. But it is an older car that I don't use as a daily drive but I do think the RNS-E is one of the best Nav units. I live where Cell reception is marginal so streaming Nav doesn't work for me most of the time so I will for the foreseeable future need a standalone Nav.
With that said in my Cayenne I installed the latest Pioneer Avic and I do like it, especially Apple Carplay w/Siri (Sorry Rian I'm still on Apple ). I mostly stream from my Iphone music and never really use the HD radio, but voice command through Siri is a definite plus. I have used Waze and Google maps in the City but the unit has new maps w/live Traffic so their isn't much of a benefit to me.
I'll keep the RS6 more old school, OEM leaning but still better than the old radio we got here in N. America.