I have had about 30 medium sized Jap commuters in the last 30 years and rate the GN400 as the best of them. It was a bit of a wreck when I bought it but a new set of rings and a cam chain sorted that out.
The longest trip I made on it was from my home here in the SW of England to Amsterdam in the Netherlands and it did about 85 mpg, that is UK gallons, 4.5 litres not US gallons, 3.9 litres and did the 700 mile round trip without a hitch.
The handling on my 12 mile commute along twisty coutry roads was great and the seat comfortable on a run. If I could go out and buy a new one tomorrow I would seriously think about it. I cannot remember the last time I saw one on the road.