The balancer problem is happening with both the VN700 and VN750. It's an age thing but there are early warnings. Some of the "pre-90s" VN750s have had it happen also.
If you start noticing vibrations or metalic noises and if you see metal shavings on the oil screen and little bits of black rubber (Always drain the oil from the side plug, it's where the oil screen is) then the dampers have started to break down.
The balancers are what keep the engine smoothed out and lessen the vibrations. When the dampeners break down the balancer "wobbles" and starts hitting casing. It will happen on all years eventually though a well ridden bike keeps those dampeners moistened. If a bike has been sitting for years, gaskets, dampeners, motor mounts, o-rings etc tend to dry out no matter what the year. I'd be cautious of a 2000 that has sat for 4-5 years.
No real concern, just something to keep in mind and check for.
Patriot Guard Rider
2000 VN750 Sere (Serendipity)
1990 GL1500 (Ole Blue)
1986 VN750 EVie (project bike, heavy custom)
VROC # 11628 / 25000-H
ARVROC # 12 Coordinator and Crowd Control
OKVROC # 18 (H)
TNVROC # 45 (H)