Plemont does close out 90% of the time, if not more. But with the surroundings, the factor of good surfable waves at low tide and the intensity of some of the waves that jack up as the swell swings into the bay, Plemont can shrink your balls like any other volatile break in the islands. Approaching high tide separates the good from the groms as the lack of beach strikes fear into people new to the bay. It can be steep, heavy and quick, so if you're board, the right conditions at Plemont could give you plenty to talk about in the cafe afterwards....which serves good grub, I agree.
This place is not just for beginners! Plemont is a cool place to practice and try out new things. If there is anywhere that closes out a lot, it's Greve!
I surfed here in Easter and the waves were really good. It is the only place on Jersey that is surfable at low tide. Great cafe at the top of the cliff.