phnuff: in the case of Sydney's Victor-1 route "The carriage and use of radio is mandatory."
I don't see that this would be very onerous for such routes where safety would be enhanced by this approach. But I would say that wouldn't I, as I don't fly non-radio aircraft! In the case of Victor-1 the alternative is to go the long way around, so if you were non-radio and you wanted to get from Sydney's northern beaches to the south coast (e.g. Wollongong) then you'd have to route inland, skirting around Sydney. This would add a considerable distance to the journey.
I'm not sure this approach would work in the LLR if there is not a viable alternative route(?), but I would suggest that addition of a frequency for those aircraft that are readio equipped to use on an opt-in basis would still enhance safety. I don't agree with your argument, that people would look out less because of relying on radio broadcasts from other traffic, as "see and avoid" still prevails, and anyway there are plenty of times (like in a circuit at an uncotrolled field on a hazy day) where we do this and still can't always spot all the traffic even when we can hear them, so we still need to LOOKOUT!
That's my vote anyway
But if this is "controversial" at the level of a PPRUNE debate, then I guess the idead has 0% chance of adoption by the CAA!
Andy