Suggestion:
Change the mechanics if UU-Matter, rather than just nerfing the EU cost up by two orders.
One of the most reasonable explanations for how UU-Matter works is that it is a blob of small, self configurable nanomachines which change can change themselves into any other material.
My suggestion:
change UU-Matter recipes to be similar to the ones from Liquid UU-Matter, where it would consist of UU-Matter + something -> more refined version of something.
A great something for general use would be scrap, considering that it appears to contain trace amounts of everything.
example: 3 UUM + 1 copper ore -> 10 copper dust.
alternate: 5 UUM + 1 Scrap -> 10 copper dust.
as for iridium, can the recipe system handle requiring more than a 1 item per stack?
if so, then do something like this: 8UUM + stack of Iron Ore => some number of iridium.
else: 8UUM + scrapbox => Iridium ore.
Also, if iridium dust is introduced, then replace iridium ore above with the dust.
DIamonds are easy enough to get as it is, so their recipe can be left alone, or could be changed to 8UUM + lots of Charcoal -> Diamond (charcoal is higher quality carbon than coal is)
Then have other mineral recipes be UUM + Scrap -> whatever dust.
Other suggestion:
UUM construction foam.
If UUM is a material made from self configurable nanomachines, then it should be possible to build with them. My suggestion is to have a machine that takes in a lot of UUM, and in it you can draw out a schematic for what needs to be built. Then activate the machine, and it sends out the UUM to build whatever shaped construction you desired. Also, the material which the UUM turns into could be set via the control machine (but limited to say stone, CF, bricks, etc)
Related suggestion:
replicating UUM
Have a way to produce replicating UUM (RUM) where you place the RUM in the world as a liquid, and it (slowly) converts surrounding blocks into more RUM. the RUM could be used like normal UUM in any recipe, but can also be used in some special ones of its own (say to multiply yields). every time the RUM converts a surrounding block, give it a chance to mutate to some other random material, which would then make it very dangerous to leave it alone, incase it decides to mutate into something explosive. Also, it would need to be contained in a self healing room as it would otherwise turn your entire world into more RUM.
Also: make it flammable then someone can burn down another players RUM factory, and then the owner can cry "Why's the RUM gone?"
or have the RUM able to move, where the source block of it can move itself into one of the non source blocks it generated, then your RUM can move around and try to escape.