It depends on your cat. Most production cruising cats accelerate at rates not much different than monohulls. Also depending on design, you may have difficulty getting clear wind to the vane due to the height of the
cabin. You may also have to think about how to structurally mount the rudder/pendulum if there is a long distance from bridgedeck to the
water.
My cat has a low bridgedeck clearance. I have an
Autohelm auxiliary
rudder wind vane that works well. It is not as responsive as on my
monohull, but does fine holding a course. In general, cats do have the advantage of tending to hold a stable course. That means the vane does not have to
work as hard.