Took the Kai Kanani early morning trip 2 years ago from Makena when staying in Wailea. Great boat and crew. No other boats around at Molokini while moored there, so snorkeling experience was pretty good. Even saw a small white tip reef shark.

BUT, can't whole-heartedly recommend them as I later found out that they've presumably done quite a bit of damage to Maui's reefs and were fined a whopping fine.
http://www.cdnn.info/news/eco/e081024a.html

Hopefully, they've cleaned up their act as they offer something very advantageous for those staying in South Maui.