Obviously there will always be a spectrum of opinion on new models versus what they are replacing. For those pleased with the Ref 3's performance there is little reason to waste time or money considering an upgrade. Who knows, the differences are so striking between the two models that maybe some might prefer the softer and more languid presentation of the 3.
I am taken by surprise however that _anyone_ could ascribe their differences as minor or inconsequential in any top system context. It would be interesting to know more about the system and circumstances of that opinion, but it came as second hand so there's no way to qualify it.
In 25 years of system building and evaluating hundreds of components I've never heard a larger difference between successive models of any component, let alone pre-amps. By comparison, the CD-7 to CD-8 upgrade was minor --though that was a pleasing and worthwhile upgrade. As I stated earlier,in my experience the difference is much closer to the difference one should expect upgrading to more powerful, refined twice-the-price amps in a system with slightly inefficient speakers.