Never a Gori prop again!
While I agree that there is a case to be made for that prop having an integral annode as part of its frame (and lets face it, this means the company is going to make a few dollars off all of its customers every year or so, in perpetuity), I think you may be a little harsh on the company for stating that they do not offer a warranty against corrosion like that.
That sort of damage is a function of where you park your boat and the habbits of the other boaters in the marina.
We crew on a boat at Brighton which does not need the annodes replaced except every second year (and they could honestly make it every third, safely), while just down the road is another yacht club with many more powerboats an such, and the annodes on a friend''s boat there get changed every six to nine months.
No one can tell you how long an annode is going to take to corrode regardless of the environment. It is entirely a function of how much stray current it is subjected to (also temp and other stuff).
I am curious that you believe that annodes mounted on the shaft will act as brakes. On the other hand, the picture shows that there is not a lot of room behind the prop on your shaft to add an annode.
Good luck in whatever you try next, but you are going to have to watch the corrossion in your area no matter who''s brand of prop you fit next (or if it is stainless or bronze).
P.S I have an Australian made Autostream 3blade feathering prop in all-stainless (with integral annode). I could not be happier with it.