I don't have a very wide bar placement on this car, but the saddles held the boat rock steady.  I didn't notice and more or less movement compared to the Thule saddles.  The other saddles on the rack are the new-style Thule H2GO saddles.   They changed the way it mounts to the bar.  They're easier to put on, but they don't grip the bar as well. 

The Guillemot with it's well-defined transition between hull and side fits down into the cradles very well.