Sorry I missed this post. I have dived there a couple of times but your best bet is to PM Greg V as he was my buddy and was much more familiar with the diving there. It was an amazing experience. I wrote a trip report viewtopic.php?f=142&t=3016&hilit=kai+iwi
(scroll down to the last dive) and if you enter 'Kai Iwi' into the search function, there is a bit more info from other members
Did you end up going at the weekend?