Paulo and others,
Thanks for your discussion of the merits of modern wide beam boats for cruising vs. the more narrow ones in previous years. Based on what you have said and shown, we'll probably see more wide beam cruising boats in the US in the future, as people over here get adjusted more to the concept that a good cruising boat doesn't have to be narrow at the stern. After looking at the information that has been presented, especially on the Opium 39, I believe that the reason that the helm must be attended closely in downwind and quartering wind on my own boat probably has to do most with the nature of the chop that we get in the shallow water, and being inshore, we tend to have considerably less wind than in an offshore situation, resulting in lower downwind speed for the boat. If the boat speed was higher, the rudder and keel would have a more pronounced effect on directional stability, and the helmsman should have less work to do maintaining course.
Yes, you are already seeing American brands going to beamy boats and bigger sterns and as European boats have a major penetration on the American market you will surely see in the future more beamy cruisers in the States.
Bavaria, Jeanneau, Dufour and Benetau are all doing cruiser models with the hull based on solo race boats and many times the designers they use are the ones that also design those racing boats.
I think you have now a pretty idea of the advantages or disadvantages of those boats in regards cruising but let me point out that the market in Europe in what regards performance cruisers is still dominated (and I think it will continue to be) by narrower boats (I have already explained the advantages).
First, Salona, Elan, Dehler, Arcona, IY, Grand soleil, Comet, X yachts and many others continue to make performance cruisers with a lot less beam than the one used on the main market cruisers using hulls not derived from the solo racers, but more "on the tradition" hulls. Brands like Pogo, Azuree or RM that make performance cruisers based on solo racers hull concept are a small minority.
So in fact you can choose your poison and what is the right compromise for you.
Regarding your boat behavior on those conditions I think you and Anders got it right. You say you have lots of chop and sea motion with not much wind and that's a difficult combination.
To have directional stability on those conditions with waves slightly on the side (following seas) you need power and speed, assuming the boat is well designed.
That has not to do with narrower or beamy hulls but with powerful boats and the Catalina is not a very powerful boat. Do that with a narrow Xp 33 (narrow boat) or with a beamy Pogo 30 or even with an Elan 320 (They may have to fly a geenaker if the wind is less than 9K) and I am sure you will have a lot of directional stability (and speed) with those boats.
Do the same with your boat with 13/15K of wind and I am almost sure that you will not have lack of directional stability and you will even be able to do that on autopilot.