I have done plenty of divining from mono and cats. My personal view is the cat is significantly easier to dive from. The reason is simple. Mono rolls, cats are much more stable. This makes it easier to load your gear and get into the water. I see no difference between mono or cat in terms of getting out of the water.

Cats also have relatively more space to store equipment and to set up.

Lastly, the party left on board during the dive will also experience less motion on a cat.