If my memory serves me correctly, and I believe it does, the Class G Airspace Trial had nothing to do with the use of radar...zip. It was all about no, zero, none, level of service in Class G airspace. Remember the National Advisory Frequency, the famed NAF? One was supposed to broadcast one's position on the NAF without reference to any third party in Class G. Now the claim is being made that it was all about more efficient use of radar. I'd dispute that claim and, instead, say it was more to do with the then flavour of the monthe - "free in G."
In fact, I believe people were chastised for calling controllers in the airspace above G (the radar controllers) for asking what the hell they should do inbound to SY/BK from the north because the procedures were a dog's breakfast. The only time radar came into the equation was when there was a near mid-air at Newcastle between an airforce aircraft and (stretching memory a bit) a DASH 8. The airforce was asked to extend radar hours to assist with the "trial" in the terminal airspace so that there wasn't a recurrence, and to prevent further embarrassment over a distinctly dodgy concept.
That's my recollection. Anyone else, barring Dick (who's given his version), have a similar view of the vaunted trial.