I think 2 up is faster in almost all conditions. I am only competitive in the very narrow wind range where I can trap upwind/fly the hull downwind and the 2 ups can't. For me this is probably 7-8 KTs.

Below this I think it becomes too difficult to position my weight far enough forward, especially on the newer hull designs with a lot of volume in the bow/less in the stern. I fell very slow in the transition range where I am on and off the trap.

Once the 2 up crews are powered up, maybe 10-12 KTs?, it is difficult to keep up and it gets worse as the wind builds from there. Usually I am completely de-powered at about 13-14 KTs and I begin to loose the ability to comfortably race the boat, round marks, ect.

I agree with Wayne that something needs to be changed in the box rules to make uni more competitive. I don't know what that is or if it is even possible.