On a nice descent, you may notice that the Shimano hubs are a bit better, given that both are well-packed and adjusted.
They really were well-made, smooth, and just appeared to have a bit higher quality control. I like my Suzues and Shimanos.
I had some Mavics, but never really rode them. I'd put the Sansins behind them, but they are easily equal to my riding abilities.
I think any difference, in reality, for me, is more imagined than perceived.