It doesn't prevent pitchpoling. No little foil is going to stop you from going over when the leeward hull goes under. In fact, the first pitchpole I did doing a jybe showed me how, of course, not to jybe in 40kt winds, but how when the wind has enough leverage to lift your boat out of the water, it will flip you on the tip of the bow, not submerge the entire hull, and the water grabs the foil and may do more harm than good.
That being said, I still have my foils on.

Jason