Lee
I have been catching reef fish for over 40 years and never use a gaff. Most times it is wise to use a large landing net especially on large pearlies (4kg+) as they are usually hooked in the soft membrane around the mouth and often the hooks pull out when lifting. Red Emperor and large snapper can be lifted if they have swallowed the hooks (snood rig) but landing net is much safer.
I have lost many large bone head snapper on top of the water (broken 7/0 hooks or frayed 80lb line).