Thanks John and W.

I understand you're saying. To get a uni rig with the same power of a sloop, the rig would be too tall to control in all but light air. Here's my next question:

Why is a uni rig more efficient upwind? Why does it point better? With a sloop, the jib helps attach air to the main better and you can sail upwind travelled all the way in. But with a uni rig, seems like I've got to travel out a bit to get the leeward tells to flow.