ZR's are great sleds...my wife has a 2000 ZR EFI 600 and loves it. Great over bumps, light and easy to toss around. May be a little harder to carve with since it only has a 121" track.
The gas milage isn't great; she gets around 8 mpg on average (Imperial gallons: 4.5L). They are also a little heavy on oil, but I would rather spend an extra $50 a season for a couple extra jugs than do a rebuild due to oil starvation.
Better to find a 700 before the year 2000 since the 600's were known for stator problems. Haven't heard much about 700 problems.
Good luck....Good riding!
