Well, I am joining this club, meaning I am going from a Ref 150 SE to a Ref 80S. Mine was ordered today and will be here in five days or so and then I will of course need to let it settle in before I can comment. My pre is a Ref 6. I am the original owner of the Ref 6 and Ref 150 SE. My dealer informs me that I should hear a significant improvement. We shall see but the truth is that I don't need the 160 watts @ 8 ohms and 70 is more than sufficient. I have an eight watt SET amp (Ampsandsound Nautilus) that provides all the power I need. So for starters that means four less very expensive KT150's to worry about ($275/each from ARC to meet ARC's stringent testing and performance criteria for these very irregular tubes!).
Something else that was not mentioned above but that is very important to me-this is the first modern ARC circuit design to fuse the output tubes. In all of my previous ARC amps dating back to a VS110 the output tubes were not only prone to arc-ing/blowing but when they did they would take out a paired resistor meant to protect the remainder of the circuit. You either had to be handy with a soldering iron or be prepared to take it in for service.
So between the hopefully better sound and all these new features paired with the sexy looks.....I had to go for it. My Ref 150 SE needs some minor service and then it is going up for sale.