It is so refreshing to hear Discap's private owner perspective! The 480B is indeed a very viable machine. It goes to show that to a large degree smoothness and reliability of a helicopter depend on having a good mechanic to look after your machine.
That of course applies to other helicopter types too. I can assure you that a well-balanced Robbie can fly as smooth and without annoying or tiresome vibrations as any 3-bladed helicopter that I have been in (H269, EN28, EH48, Cabri G2, AS341). I agree though that the rotor head, and the overall weight, make the 480B less susceptible to turbulence than it's two-bladed hangar companions.
How does 3.5 HRS of fuel and 500 lbs in the cabin compare? Well, out of all the machines you mentioned, only the R66 can carry 3.5 HRS of fuel at all.
While you correctly say that the 480B is not your typically cattle mustering machine, Dennis Kenyon has shown us that it is nonetheless highly manoeuvrable: