Interesting idea. We know that Amas are not all balanced equally.
Putting your wife's observations aside for the moment, lots of other factors would influence the tendency to dive (and trump any possible imbalance in the hull).
Your sail trim/state of furl has a huge influence downwind
Your direction relative to the trailing waves (small degrees = big difference)
The distribution of weight in the hull (both you and the cargo)
Water in the hull, at any given time
Possibly your "drive" and dagger positions (I know, I know,.. )
And, no offense meant, but your buds may just be better surfers.
So you will never really have exactly the same factors on any 2 AI's, at any given time.
Next time you sail, if you adjust some of the physical factors you may see an improvement right away. More than anything, just laying back as far as you can while cresting the waves will rebalance the boat immediately and give you a better ride, as will steering off a little and spilling some air.
You are not going to be able to do anything about the hull anyway, so I would explore repositioning your weight load (low and to the rear) to find a better tipping point. Since you are the "movable ballast", maybe it's time to experiment with a rear seat or tramp position, you might really enjoy the drier ride and the new view as well. I sure do.
If anything, your hull just may be a little faster than others for some reason, such as color (I know, I know,..)