I just think it is a shame that they are so good as it has made all older versions not as competitive (or perceived to be as competitive). 8 out of the top 10 in Weymouth were Mark IV. I guess it is partly because a lot of good sailors have bought them but that is because they are faster most probably.
I think you are missing the point – before the Mk4 the best sailors had to hunt round for the best wooden boat and a number were believed to give an advantage in certain sailing conditions by the variations in shape. I believe we had a “good” wooden boat just did not sail it as well as some others but it was bad for the class that to ensure you had the most competitive boat you had to search around for the best 20yr old wooden boat. Most of the sailors at the front of the fleet deserved to be there but it was never possible to determine how much the helm/crew and how much the boat contributed to any win or race position. With the Mk IV its a completely level playing field with the general perception that the MkIV is easier to sail, easier to sail out any water and possibly marginally faster but I think the helm is still the biggest factor and any good helm can now buy a MkIV and expect to (win knowing that its as good as any other MkIV) providing they are the best helm/crew that day.