New application: Should I use Three20 or raw UIKit?

I’ve been considering starting a new project recently, and have been torn: Should I create my project using Three20, or should I use UIKit directly?  I know Three20 is supposed to help by making applications easier to develop, but what does it really buy me as a developer?  In my experience, most of my time with Three20 has been spent working around its various quirks.  And from what I can tell from my recent research, it doesn’t seem so straight-forward to support Universal applications across iPhone and iPad devices.

The application I’m considering building needs to use a splitview controller, popover controllers, and all the standard UI metaphors from the iPad.  Those don’t seem to be Three20’s strong-suit.  Does anyone have any ideas on how to elegantly support Universal applications using Three20?

For the time being, I’m hoping to develop using Apple’s standard stack, perhaps even using Interface Builder to define my custom table cells and views.  My hope is that Xcode 4, once its released, will improve on Interface Builder’s integration with Xcode, making development with it less painful.