I have been following this thread with great interest. I had spent many years searching for the "perfect" boat...FOR ME. What I may find ideal, others may find, well, odd. I follow what Jeff H is saying, and my final choice would be somewhat in line with what he has been saying here. I have a 37'' boat that displaces roughly 11,000# with about 5,500# in her keel. This boat is very easily driven, and works well in almost all conditions.
When it comes to loading up 2,000# worth of gear, two things will affect that the most. First, hull form. A boat with greater wetted surface, (you know, the part below the waterline) will be able to better support the additional weight. My light weight boat may be able to better support the addtional weight than the heavier boat due to my wider beam and greater surface I have to support the addtional weight. So the increase in weight may have less of an impact on the hull being "pressed into" the water. You would see less of a change in my waterline, so to speak.
The second is where the additional weight is placed. I may be a little off the mark, but if all that weight is stowed high up and away from the CG of the vessel, it will make the boat less stable. Keeping the weight close to the boats CG will have less of an effect on the boats stability.
I have sailed "traditional" designs in rough weather, and while they have slower motions through the water, I have usually found them to be wet rides. Plowing through waves and heavy chop as opposed to riding over them. Many more "Greenies" rolling aft than on a lighter design.
But there is no perfect design, for if there were, we would all be sailing the same thing!
I like lighter weight, easily driven designs. You can still have a robust vessel that just doesn''t weigh alot. The other day, I was out in 25-30kts with a 3-5''chop. Just my main, and I was cruising quite comfortably at 7kts. I watched as heavier, "Cruising" designs were struggling to keep up with reefed mains and luffing jibs. My passengers and I were having a wonderful time, t-shirts and bathing suits, enjoying the blustery day, while the "Cruisers" were hunkered down in full foulies, getting soaked. Hey, to each there own!