I feel that I may have a definative answer to the original question:
Q. "How wide is too wide?"
A. "wide enough for you to poach MY line is too wide." If I am competing with you for fresh tracks, your skis are too wide and you should go back to short carving skis and stick to practicing 'cross under/ cross over' drills on blue groomers.*
* denotes sarcasm on my part. Don't get riled up, I'm Kidding.