Why a larger carrier might favor Hawkeye over an improved Gannet

Would an improved Gannet have remained Britain's airborne-early-warning aircraft on a Malta-sized carrier?

Probably not necessarily; the larger deck could have supported the E-2 Hawkeye, removing the size-driven reason to persist with Gannet.

The Gannet remained attractive partly because British carriers were small. A Malta-sized deck would have reduced that constraint and made adoption of the larger E-2 Hawkeye more practical, potentially with British radar equipment.