Well I've read a bit on the subject of jibing and broaching in my Wayfarer 16ft centreboard sloop (no keel).
The consensus seems to be that keeping the centreboard down during a run enhances directional stability, making a broach and death roll less likely.
I had problems with it coming up of it's own accord on a run, so installed some shockcord to hold it down.
The other tips for not broaching were :
Never overtake waves on a run. The boat makes the waves break, then the rudder ends up in aerated water, losing it's effect. Slow down if you seem to be overtaking waves.
If it's really windy, jib only for the run can work well.
If it's at all windy, just don't jibe. Do a chicken jibe instead.