How OU are created ? They are created because they are Over Used on PVP.
If you create a ladder for UU, it will just be a new meta in the UU; some PKM will just be Over Used on the UU Ladder.
In all case, will it change the economy? "the Demand for them will increase, the values will be high for them"
In theory, it work like this, in practice, prices are not with demand and offer. Let's face it, on PRO prices depend of the sense of the wind and the amount of money in the economy.