Depends on what end you want to fish really, as above up at the lighthouse end you can fish a 2-3 metre swell where as at the other end near the 'gap' you wouldn't want anything more than 1m really. Although dry on the fishing spot it's a bit iffy getting back without getting wet in a bigger swell.
To be honest I've found the fishing at the gap end better as it's a sandy bottom without the snags, ledges and overhangs of the lighthouse end. It's also easier to get down and gaff/net a bigger fish.
Also I reckon swell direction makes a huge difference in the amount of water coming over the low spots, pretty much due to the angle the swell hits the ledge. Same applies to tide really sometimes less water comes over on high for some reason and the high spots generally stay dry if it's fish able.
You might need to sit tight in your spot if the tide is right in and its a bit sloppy tho .
As long as you use common sense and walk along the base of the rocks when moving along the reef and don't panic if one comes over you're pretty safe.