hmmm... It seems that too many people forget one thing...
What is your monitor refresh rate?
If you have a flat panel you probably have a ~70Hz refresh rate. That means your monitor is showing 70 images per second.
What happens if your graphic card generate *put whatever high number you want in here* FPS? really nothing, your monitor is still showing 70 images per second.
So, for me, does not make sense that some people get smoother sensation when running at 250 FPS than running at 80 FPS cause they are seeing 70 images per second in both cases
If I'm wrong please let me now
To be on topic... You may activate VSync only if you're getting page tearing (or in older games), but you may activate FPS limit and set it to 100 (for example) to prevent graphic card work for nothing