Looks like your boat is big. Unless you have lots of crew that can hand steer, you'll eventually need one. My teenage kids
like to steer - for awhile, when it's nice. Eventually it will break or you'll run out of juice.
A wind vane uses the same thing that powers your boat. Unlike an auotpilot, the vane follows the wind, so sail trimming is not as necessary as with a AP.
Most importantly to me, is that the harder it blows, the weaker a AP gets but the stronger a vane gets. Typically vanes are very well-built and can take years of use.
They both have their place and if you have a AP, that's great, especially for motoring, but don't go offshore
without a vane (or a spare AP or 2). It will amaze you at how well it can steer hour after hour. Just don't expect it to stay within 2 degrees of your course like your AP. Vanes steer an average course.
Even in the Caribbean
they are useful - our last trip to the Bahamas
was an overnighter and the AP could never have handled the conditions. We'd have been wiped out the next day if we'd have hand steered.