I spent a couple of weeks on Moyo back in 2010. The resort was very quite so I had a one on one with the dive guides, Kaz and Elias, which made my photographic opportunities excellent.
Viz was good, and a wide range of critters from pigmy sea horses to blue spotted rays. The coral is very colourful with some really large barrel sponges.
The only issue I had was the weight of luggage flying in from Bali. I bought an extra seat both ways just in case so that i could carry all my gear. In the end it wasn't a problem as we were the only passengers on the plane.
Have a great trip