Two things from a theoretical perspective. (Which is all I've got since I a) hardly have any time on my cat and b) it's neither an N5.5 uni or sl)

1. I would assume that the uni rig is balanced for and aft with the daggers. Wouldn't simply tossing a jib out front shift the combined center of effort too far forward with out radically raking the mast or relocating the daggers?

2. It's my understanding of aerodynamics that a non-slotted, high aspect ratio wing (uni rig) can out point a slotted, lower aspect ratio wing (slope rig). Why give that up?