This is one of the worst game design ideas ever. The only difference between Omega Items and Uniques will be a Special Affix for Powers. Does somoeone really needs a piercing minigun or a trap on a roll with 10 seconds cooldown? You better take +5 to different Attributes.
Why don't you add an Omega Cube on Unique items so you can add the Piercing Minigun Effect?
Why don't let us craft and buff Uniques? Let's say Level 1 Unique gives +1 To Fighting and Level 10 Unique +10 to Fighting. For a Level 10 Unique you could need 100 Uniques to craft.